add utils.ajax_error_msg for extracting the JSON error message.

IPython/html/static/base/js/utils.js

@@ -1,557 +1,563
 // Copyright (c) IPython Development Team.
 // Distributed under the terms of the Modified BSD License.
 
 define([
     'base/js/namespace',
     'jquery',
 ], function(IPython, $){
     "use strict";
     
     IPython.load_extensions = function () {
         // load one or more IPython notebook extensions with requirejs
         
         var extensions = [];
         var extension_names = arguments;
         for (var i = 0; i < extension_names.length; i++) {
             extensions.push("nbextensions/" + arguments[i]);
         }
         
         require(extensions,
             function () {
                 for (var i = 0; i < arguments.length; i++) {
                     var ext = arguments[i];
                     var ext_name = extension_names[i];
                     // success callback
                     console.log("Loaded extension: " + ext_name);
                     if (ext && ext.load_ipython_extension !== undefined) {
                         ext.load_ipython_extension();
                     }
                 }
             },
             function (err) {
                 // failure callback
                 console.log("Failed to load extension(s):", err.requireModules, err);
             }
         );
     };
 
     //============================================================================
     // Cross-browser RegEx Split
     //============================================================================
 
     // This code has been MODIFIED from the code licensed below to not replace the
     // default browser split.  The license is reproduced here.
 
     // see http://blog.stevenlevithan.com/archives/cross-browser-split for more info:
     /*!
      * Cross-Browser Split 1.1.1
      * Copyright 2007-2012 Steven Levithan <stevenlevithan.com>
      * Available under the MIT License
      * ECMAScript compliant, uniform cross-browser split method
      */
 
     /**
      * Splits a string into an array of strings using a regex or string
      * separator. Matches of the separator are not included in the result array.
      * However, if `separator` is a regex that contains capturing groups,
      * backreferences are spliced into the result each time `separator` is
      * matched. Fixes browser bugs compared to the native
      * `String.prototype.split` and can be used reliably cross-browser.
      * @param {String} str String to split.
      * @param {RegExp|String} separator Regex or string to use for separating
      *     the string.
      * @param {Number} [limit] Maximum number of items to include in the result
      *     array.
      * @returns {Array} Array of substrings.
      * @example
      *
      * // Basic use
      * regex_split('a b c d', ' ');
      * // -> ['a', 'b', 'c', 'd']
      *
      * // With limit
      * regex_split('a b c d', ' ', 2);
      * // -> ['a', 'b']
      *
      * // Backreferences in result array
      * regex_split('..word1 word2..', /([a-z]+)(\d+)/i);
      * // -> ['..', 'word', '1', ' ', 'word', '2', '..']
      */
     var regex_split = function (str, separator, limit) {
         // If `separator` is not a regex, use `split`
         if (Object.prototype.toString.call(separator) !== "[object RegExp]") {
             return split.call(str, separator, limit);
         }
         var output = [],
             flags = (separator.ignoreCase ? "i" : "") +
                     (separator.multiline  ? "m" : "") +
                     (separator.extended   ? "x" : "") + // Proposed for ES6
                     (separator.sticky     ? "y" : ""), // Firefox 3+
             lastLastIndex = 0,
             // Make `global` and avoid `lastIndex` issues by working with a copy
             separator = new RegExp(separator.source, flags + "g"),
             separator2, match, lastIndex, lastLength;
         str += ""; // Type-convert
 
         var compliantExecNpcg = typeof(/()??/.exec("")[1]) === "undefined";
         if (!compliantExecNpcg) {
             // Doesn't need flags gy, but they don't hurt
             separator2 = new RegExp("^" + separator.source + "$(?!\\s)", flags);
         }
         /* Values for `limit`, per the spec:
          * If undefined: 4294967295 // Math.pow(2, 32) - 1
          * If 0, Infinity, or NaN: 0
          * If positive number: limit = Math.floor(limit); if (limit > 4294967295) limit -= 4294967296;
          * If negative number: 4294967296 - Math.floor(Math.abs(limit))
          * If other: Type-convert, then use the above rules
          */
         limit = typeof(limit) === "undefined" ?
             -1 >>> 0 : // Math.pow(2, 32) - 1
             limit >>> 0; // ToUint32(limit)
         while (match = separator.exec(str)) {
             // `separator.lastIndex` is not reliable cross-browser
             lastIndex = match.index + match[0].length;
             if (lastIndex > lastLastIndex) {
                 output.push(str.slice(lastLastIndex, match.index));
                 // Fix browsers whose `exec` methods don't consistently return `undefined` for
                 // nonparticipating capturing groups
                 if (!compliantExecNpcg && match.length > 1) {
                     match[0].replace(separator2, function () {
                         for (var i = 1; i < arguments.length - 2; i++) {
                             if (typeof(arguments[i]) === "undefined") {
                                 match[i] = undefined;
                             }
                         }
                     });
                 }
                 if (match.length > 1 && match.index < str.length) {
                     Array.prototype.push.apply(output, match.slice(1));
                 }
                 lastLength = match[0].length;
                 lastLastIndex = lastIndex;
                 if (output.length >= limit) {
                     break;
                 }
             }
             if (separator.lastIndex === match.index) {
                 separator.lastIndex++; // Avoid an infinite loop
             }
         }
         if (lastLastIndex === str.length) {
             if (lastLength || !separator.test("")) {
                 output.push("");
             }
         } else {
             output.push(str.slice(lastLastIndex));
         }
         return output.length > limit ? output.slice(0, limit) : output;
     };
 
     //============================================================================
     // End contributed Cross-browser RegEx Split
     //============================================================================
 
 
     var uuid = function () {
         // http://www.ietf.org/rfc/rfc4122.txt
         var s = [];
         var hexDigits = "0123456789ABCDEF";
         for (var i = 0; i < 32; i++) {
             s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
         }
         s[12] = "4";  // bits 12-15 of the time_hi_and_version field to 0010
         s[16] = hexDigits.substr((s[16] & 0x3) | 0x8, 1);  // bits 6-7 of the clock_seq_hi_and_reserved to 01
 
         var uuid = s.join("");
         return uuid;
     };
 
 
     //Fix raw text to parse correctly in crazy XML
     function xmlencode(string) {
         return string.replace(/\&/g,'&'+'amp;')
             .replace(/</g,'&'+'lt;')
             .replace(/>/g,'&'+'gt;')
             .replace(/\'/g,'&'+'apos;')
             .replace(/\"/g,'&'+'quot;')
             .replace(/`/g,'&'+'#96;');
     }
 
 
     //Map from terminal commands to CSS classes
     var ansi_colormap = {
         "01":"ansibold",
         
         "30":"ansiblack",
         "31":"ansired",
         "32":"ansigreen",
         "33":"ansiyellow",
         "34":"ansiblue",
         "35":"ansipurple",
         "36":"ansicyan",
         "37":"ansigray",
         
         "40":"ansibgblack",
         "41":"ansibgred",
         "42":"ansibggreen",
         "43":"ansibgyellow",
         "44":"ansibgblue",
         "45":"ansibgpurple",
         "46":"ansibgcyan",
         "47":"ansibggray"
     };
     
     function _process_numbers(attrs, numbers) {
         // process ansi escapes
         var n = numbers.shift();
         if (ansi_colormap[n]) {
             if ( ! attrs["class"] ) {
                 attrs["class"] = ansi_colormap[n];
             } else {
                 attrs["class"] += " " + ansi_colormap[n];
             }
         } else if (n == "38" || n == "48") {
             // VT100 256 color or 24 bit RGB
             if (numbers.length < 2) {
                 console.log("Not enough fields for VT100 color", numbers);
                 return;
             }
             
             var index_or_rgb = numbers.shift();
             var r,g,b;
             if (index_or_rgb == "5") {
                 // 256 color
                 var idx = parseInt(numbers.shift());
                 if (idx < 16) {
                     // indexed ANSI
                     // ignore bright / non-bright distinction
                     idx = idx % 8;
                     var ansiclass = ansi_colormap[n[0] + (idx % 8).toString()];
                     if ( ! attrs["class"] ) {
                         attrs["class"] = ansiclass;
                     } else {
                         attrs["class"] += " " + ansiclass;
                     }
                     return;
                 } else if (idx < 232) {
                     // 216 color 6x6x6 RGB
                     idx = idx - 16;
                     b = idx % 6;
                     g = Math.floor(idx / 6) % 6;
                     r = Math.floor(idx / 36) % 6;
                     // convert to rgb
                     r = (r * 51);
                     g = (g * 51);
                     b = (b * 51);
                 } else {
                     // grayscale
                     idx = idx - 231;
                     // it's 1-24 and should *not* include black or white,
                     // so a 26 point scale
                     r = g = b = Math.floor(idx * 256 / 26);
                 }
             } else if (index_or_rgb == "2") {
                 // Simple 24 bit RGB
                 if (numbers.length > 3) {
                     console.log("Not enough fields for RGB", numbers);
                     return;
                 }
                 r = numbers.shift();
                 g = numbers.shift();
                 b = numbers.shift();
             } else {
                 console.log("unrecognized control", numbers);
                 return;
             }
             if (r !== undefined) {
                 // apply the rgb color
                 var line;
                 if (n == "38") {
                     line = "color: ";
                 } else {
                     line = "background-color: ";
                 }
                 line = line + "rgb(" + r + "," + g + "," + b + ");"
                 if ( !attrs["style"] ) {
                     attrs["style"] = line;
                 } else {
                     attrs["style"] += " " + line;
                 }
             }
         }
     }
 
     function ansispan(str) {
         // ansispan function adapted from github.com/mmalecki/ansispan (MIT License)
         // regular ansi escapes (using the table above)
         return str.replace(/\033\[(0?[01]|22|39)?([;\d]+)?m/g, function(match, prefix, pattern) {
             if (!pattern) {
                 // [(01|22|39|)m close spans
                 return "</span>";
             }
             // consume sequence of color escapes
             var numbers = pattern.match(/\d+/g);
             var attrs = {};
             while (numbers.length > 0) {
                 _process_numbers(attrs, numbers);
             }
             
             var span = "<span ";
             for (var attr in attrs) {
                 var value = attrs[attr];
                 span = span + " " + attr + '="' + attrs[attr] + '"';
             }
             return span + ">";
         });
     };
     
     // Transform ANSI color escape codes into HTML <span> tags with css
     // classes listed in the above ansi_colormap object. The actual color used
     // are set in the css file.
     function fixConsole(txt) {
         txt = xmlencode(txt);
         var re = /\033\[([\dA-Fa-f;]*?)m/;
         var opened = false;
         var cmds = [];
         var opener = "";
         var closer = "";
 
         // Strip all ANSI codes that are not color related.  Matches
         // all ANSI codes that do not end with "m".
         var ignored_re = /(?=(\033\[[\d;=]*[a-ln-zA-Z]{1}))\1(?!m)/g;
         txt = txt.replace(ignored_re, "");
         
         // color ansi codes
         txt = ansispan(txt);
         return txt;
     }
 
     // Remove chunks that should be overridden by the effect of
     // carriage return characters
     function fixCarriageReturn(txt) {
         var tmp = txt;
         do {
             txt = tmp;
             tmp = txt.replace(/\r+\n/gm, '\n'); // \r followed by \n --> newline
             tmp = tmp.replace(/^.*\r+/gm, '');  // Other \r --> clear line
         } while (tmp.length < txt.length);
         return txt;
     }
 
     // Locate any URLs and convert them to a anchor tag
     function autoLinkUrls(txt) {
         return txt.replace(/(^|\s)(https?|ftp)(:[^'">\s]+)/gi,
             "$1<a target=\"_blank\" href=\"$2$3\">$2$3</a>");
     }
 
     var points_to_pixels = function (points) {
         // A reasonably good way of converting between points and pixels.
         var test = $('<div style="display: none; width: 10000pt; padding:0; border:0;"></div>');
         $(body).append(test);
         var pixel_per_point = test.width()/10000;
         test.remove();
         return Math.floor(points*pixel_per_point);
     };
     
     var always_new = function (constructor) {
         // wrapper around contructor to avoid requiring `var a = new constructor()`
         // useful for passing constructors as callbacks,
         // not for programmer laziness.
         // from http://programmers.stackexchange.com/questions/118798
         return function () {
             var obj = Object.create(constructor.prototype);
             constructor.apply(obj, arguments);
             return obj;
         };
     };
 
     var url_path_join = function () {
         // join a sequence of url components with '/'
         var url = '';
         for (var i = 0; i < arguments.length; i++) {
             if (arguments[i] === '') {
                 continue;
             }
             if (url.length > 0 && url[url.length-1] != '/') {
                 url = url + '/' + arguments[i];
             } else {
                 url = url + arguments[i];
             }
         }
         url = url.replace(/\/\/+/, '/');
         return url;
     };
     
     var parse_url = function (url) {
         // an `a` element with an href allows attr-access to the parsed segments of a URL
         // a = parse_url("http://localhost:8888/path/name#hash")
         // a.protocol = "http:"
         // a.host     = "localhost:8888"
         // a.hostname = "localhost"
         // a.port     = 8888
         // a.pathname = "/path/name"
         // a.hash     = "#hash"
         var a = document.createElement("a");
         a.href = url;
         return a;
     };
     
     var encode_uri_components = function (uri) {
         // encode just the components of a multi-segment uri,
         // leaving '/' separators
         return uri.split('/').map(encodeURIComponent).join('/');
     };
     
     var url_join_encode = function () {
         // join a sequence of url components with '/',
         // encoding each component with encodeURIComponent
         return encode_uri_components(url_path_join.apply(null, arguments));
     };
 
 
     var splitext = function (filename) {
         // mimic Python os.path.splitext
         // Returns ['base', '.ext']
         var idx = filename.lastIndexOf('.');
         if (idx > 0) {
             return [filename.slice(0, idx), filename.slice(idx)];
         } else {
             return [filename, ''];
         }
     };
 
 
     var escape_html = function (text) {
         // escape text to HTML
         return $("<div/>").text(text).html();
     };
 
 
     var get_body_data = function(key) {
         // get a url-encoded item from body.data and decode it
         // we should never have any encoded URLs anywhere else in code
         // until we are building an actual request
         return decodeURIComponent($('body').data(key));
     };
     
     var to_absolute_cursor_pos = function (cm, cursor) {
         // get the absolute cursor position from CodeMirror's col, ch
         if (!cursor) {
             cursor = cm.getCursor();
         }
         var cursor_pos = cursor.ch;
         for (var i = 0; i < cursor.line; i++) {
             cursor_pos += cm.getLine(i).length + 1;
         }
         return cursor_pos;
     };
     
     var from_absolute_cursor_pos = function (cm, cursor_pos) {
         // turn absolute cursor postion into CodeMirror col, ch cursor
         var i, line;
         var offset = 0;
         for (i = 0, line=cm.getLine(i); line !== undefined; i++, line=cm.getLine(i)) {
             if (offset + line.length < cursor_pos) {
                 offset += line.length + 1;
             } else {
                 return {
                     line : i,
                     ch : cursor_pos - offset,
                 };
             }
         }
         // reached end, return endpoint
         return {
             ch : line.length - 1,
             line : i - 1,
         };
     };
     
     // http://stackoverflow.com/questions/2400935/browser-detection-in-javascript
     var browser = (function() {
         if (typeof navigator === 'undefined') {
             // navigator undefined in node
             return 'None';
         }
         var N= navigator.appName, ua= navigator.userAgent, tem;
         var M= ua.match(/(opera|chrome|safari|firefox|msie)\/?\s*(\.?\d+(\.\d+)*)/i);
         if (M && (tem= ua.match(/version\/([\.\d]+)/i)) !== null) M[2]= tem[1];
         M= M? [M[1], M[2]]: [N, navigator.appVersion,'-?'];
         return M;
     })();
 
     // http://stackoverflow.com/questions/11219582/how-to-detect-my-browser-version-and-operating-system-using-javascript
     var platform = (function () {
         if (typeof navigator === 'undefined') {
             // navigator undefined in node
             return 'None';
         }
         var OSName="None";
         if (navigator.appVersion.indexOf("Win")!=-1) OSName="Windows";
         if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";
         if (navigator.appVersion.indexOf("X11")!=-1) OSName="UNIX";
         if (navigator.appVersion.indexOf("Linux")!=-1) OSName="Linux";
         return OSName;
     })();
 
     var is_or_has = function (a, b) {
         // Is b a child of a or a itself?
         return a.has(b).length !==0 || a.is(b);
     };
 
     var is_focused = function (e) {
         // Is element e, or one of its children focused?
         e = $(e);
         var target = $(document.activeElement);
         if (target.length > 0) {
             if (is_or_has(e, target)) {
                 return true;
             } else {
                 return false;
             }
         } else {
             return false;
         }
     };
     
+    var ajax_error_msg = function (jqXHR) {
+        // Return a JSON error message if there is one,
+        // otherwise the basic HTTP status text.
+        if (jqXHR.responseJSON && jqXHR.responseJSON.message) {
+            return jqXHR.responseJSON.message;
+        } else {
+            return jqXHR.statusText;
+        }
+    }
     var log_ajax_error = function (jqXHR, status, error) {
         // log ajax failures with informative messages
         var msg = "API request failed (" + jqXHR.status + "): ";
         console.log(jqXHR);
-        if (jqXHR.responseJSON && jqXHR.responseJSON.message) {
-            msg += jqXHR.responseJSON.message;
-        } else {
-            msg += jqXHR.statusText;
-        }
+        msg += ajax_error_msg(jqXHR);
         console.log(msg);
     };
 
     var utils = {
         regex_split : regex_split,
         uuid : uuid,
         fixConsole : fixConsole,
         fixCarriageReturn : fixCarriageReturn,
         autoLinkUrls : autoLinkUrls,
         points_to_pixels : points_to_pixels,
         get_body_data : get_body_data,
         parse_url : parse_url,
         url_path_join : url_path_join,
         url_join_encode : url_join_encode,
         encode_uri_components : encode_uri_components,
         splitext : splitext,
         escape_html : escape_html,
         always_new : always_new,
         to_absolute_cursor_pos : to_absolute_cursor_pos,
         from_absolute_cursor_pos : from_absolute_cursor_pos,
         browser : browser,
         platform: platform,
         is_or_has : is_or_has,
         is_focused : is_focused,
+        ajax_error_msg : ajax_error_msg,
         log_ajax_error : log_ajax_error,
     };
 
     // Backwards compatability.
     IPython.utils = utils;
     
     return utils;
 }); 

IPython/html/static/notebook/js/notebook.js

@@ -1,2585 +1,2582
 // Copyright (c) IPython Development Team.
 // Distributed under the terms of the Modified BSD License.
 
 define([
     'base/js/namespace',
     'jquery',
     'base/js/utils',
     'base/js/dialog',
     'notebook/js/textcell',
     'notebook/js/codecell',
     'services/sessions/js/session',
     'notebook/js/celltoolbar',
     'components/marked/lib/marked',
     'highlight',
     'notebook/js/mathjaxutils',
     'base/js/keyboard',
     'notebook/js/tooltip',
     'notebook/js/celltoolbarpresets/default',
     'notebook/js/celltoolbarpresets/rawcell',
     'notebook/js/celltoolbarpresets/slideshow',
 ], function (
     IPython, 
     $, 
     utils, 
     dialog, 
     textcell, 
     codecell, 
     session, 
     celltoolbar, 
     marked,
     hljs,
     mathjaxutils,
     keyboard,
     tooltip,
     default_celltoolbar,
     rawcell_celltoolbar,
     slideshow_celltoolbar
     ) {
 
     var Notebook = function (selector, options) {
         // Constructor
         //
         // A notebook contains and manages cells.
         //
         // Parameters:
         //  selector: string
         //  options: dictionary
         //      Dictionary of keyword arguments.
         //          events: $(Events) instance
         //          keyboard_manager: KeyboardManager instance
         //          save_widget: SaveWidget instance
         //          config: dictionary
         //          base_url : string
         //          notebook_path : string
         //          notebook_name : string
         this.config = options.config || {};
         this.base_url = options.base_url;
         this.notebook_path = options.notebook_path;
         this.notebook_name = options.notebook_name;
         this.events = options.events;
         this.keyboard_manager = options.keyboard_manager;
         this.save_widget = options.save_widget;
         this.tooltip = new tooltip.Tooltip(this.events);
         this.ws_url = options.ws_url;
         // default_kernel_name is a temporary measure while we implement proper
         // kernel selection and delayed start. Do not rely on it.
         this.default_kernel_name = 'python';
         // TODO: This code smells (and the other `= this` line a couple lines down)
         // We need a better way to deal with circular instance references.
         this.keyboard_manager.notebook = this;
         this.save_widget.notebook = this;
         
         mathjaxutils.init();
 
         if (marked) {
             marked.setOptions({
                 gfm : true,
                 tables: true,
                 langPrefix: "language-",
                 highlight: function(code, lang) {
                     if (!lang) {
                         // no language, no highlight
                         return code;
                     }
                     var highlighted;
                     try {
                         highlighted = hljs.highlight(lang, code, false);
                     } catch(err) {
                         highlighted = hljs.highlightAuto(code);
                     }
                     return highlighted.value;
                 }
             });
         }
 
         this.element = $(selector);
         this.element.scroll();
         this.element.data("notebook", this);
         this.next_prompt_number = 1;
         this.session = null;
         this.kernel = null;
         this.clipboard = null;
         this.undelete_backup = null;
         this.undelete_index = null;
         this.undelete_below = false;
         this.paste_enabled = false;
         // It is important to start out in command mode to match the intial mode
         // of the KeyboardManager.
         this.mode = 'command';
         this.set_dirty(false);
         this.metadata = {};
         this._checkpoint_after_save = false;
         this.last_checkpoint = null;
         this.checkpoints = [];
         this.autosave_interval = 0;
         this.autosave_timer = null;
         // autosave *at most* every two minutes
         this.minimum_autosave_interval = 120000;
         // single worksheet for now
         this.worksheet_metadata = {};
         this.notebook_name_blacklist_re = /[\/\\:]/;
         this.nbformat = 3; // Increment this when changing the nbformat
         this.nbformat_minor = 0; // Increment this when changing the nbformat
         this.codemirror_mode = 'ipython';
         this.create_elements();
         this.bind_events();
         this.save_notebook = function() { // don't allow save until notebook_loaded
             this.save_notebook_error(null, null, "Load failed, save is disabled");
         };
 
         // Trigger cell toolbar registration.
         default_celltoolbar.register(this);
         rawcell_celltoolbar.register(this);
         slideshow_celltoolbar.register(this);
     };
 
 
     /**
      * Create an HTML and CSS representation of the notebook.
      * 
      * @method create_elements
      */
     Notebook.prototype.create_elements = function () {
         var that = this;
         this.element.attr('tabindex','-1');
         this.container = $("<div/>").addClass("container").attr("id", "notebook-container");
         // We add this end_space div to the end of the notebook div to:
         // i) provide a margin between the last cell and the end of the notebook
         // ii) to prevent the div from scrolling up when the last cell is being
         // edited, but is too low on the page, which browsers will do automatically.
         var end_space = $('<div/>').addClass('end_space');
         end_space.dblclick(function (e) {
             var ncells = that.ncells();
             that.insert_cell_below('code',ncells-1);
         });
         this.element.append(this.container);
         this.container.append(end_space);
     };
 
     /**
      * Bind JavaScript events: key presses and custom IPython events.
      * 
      * @method bind_events
      */
     Notebook.prototype.bind_events = function () {
         var that = this;
 
         this.events.on('set_next_input.Notebook', function (event, data) {
             var index = that.find_cell_index(data.cell);
             var new_cell = that.insert_cell_below('code',index);
             new_cell.set_text(data.text);
             that.dirty = true;
         });
 
         this.events.on('set_dirty.Notebook', function (event, data) {
             that.dirty = data.value;
         });
 
         this.events.on('trust_changed.Notebook', function (event, data) {
             that.trusted = data.value;
         });
 
         this.events.on('select.Cell', function (event, data) {
             var index = that.find_cell_index(data.cell);
             that.select(index);
         });
 
         this.events.on('edit_mode.Cell', function (event, data) {
             that.handle_edit_mode(data.cell);
         });
 
         this.events.on('command_mode.Cell', function (event, data) {
             that.handle_command_mode(data.cell);
         });
 
         this.events.on('status_autorestarting.Kernel', function () {
             dialog.modal({
                 notebook: that,
                 keyboard_manager: that.keyboard_manager,
                 title: "Kernel Restarting",
                 body: "The kernel appears to have died. It will restart automatically.",
                 buttons: {
                     OK : {
                         class : "btn-primary"
                     }
                 }
             });
         });
         
         this.events.on('spec_changed.Kernel', function(event, data) {
             that.set_kernelspec_metadata(data);
             if (data.codemirror_mode) {
                 that.set_codemirror_mode(data.codemirror_mode);
             }
         });
 
         var collapse_time = function (time) {
             var app_height = $('#ipython-main-app').height(); // content height
             var splitter_height = $('div#pager_splitter').outerHeight(true);
             var new_height = app_height - splitter_height;
             that.element.animate({height : new_height + 'px'}, time);
         };
 
         this.element.bind('collapse_pager', function (event, extrap) {
             var time = (extrap !== undefined) ? ((extrap.duration !== undefined ) ? extrap.duration : 'fast') : 'fast';
             collapse_time(time);
         });
 
         var expand_time = function (time) {
             var app_height = $('#ipython-main-app').height(); // content height
             var splitter_height = $('div#pager_splitter').outerHeight(true);
             var pager_height = $('div#pager').outerHeight(true);
             var new_height = app_height - pager_height - splitter_height;
             that.element.animate({height : new_height + 'px'}, time);
         };
 
         this.element.bind('expand_pager', function (event, extrap) {
             var time = (extrap !== undefined) ? ((extrap.duration !== undefined ) ? extrap.duration : 'fast') : 'fast';
             expand_time(time);
         });
         
         // Firefox 22 broke $(window).on("beforeunload")
         // I'm not sure why or how.
         window.onbeforeunload = function (e) {
             // TODO: Make killing the kernel configurable.
             var kill_kernel = false;
             if (kill_kernel) {
                 that.session.kill_kernel();
             }
             // if we are autosaving, trigger an autosave on nav-away.
             // still warn, because if we don't the autosave may fail.
             if (that.dirty) {
                 if ( that.autosave_interval ) {
                     // schedule autosave in a timeout
                     // this gives you a chance to forcefully discard changes
                     // by reloading the page if you *really* want to.
                     // the timer doesn't start until you *dismiss* the dialog.
                     setTimeout(function () {
                         if (that.dirty) {
                             that.save_notebook();
                         }
                     }, 1000);
                     return "Autosave in progress, latest changes may be lost.";
                 } else {
                     return "Unsaved changes will be lost.";
                 }
             }
             // Null is the *only* return value that will make the browser not
             // pop up the "don't leave" dialog.
             return null;
         };
     };
 
     /**
      * Set the dirty flag, and trigger the set_dirty.Notebook event
      * 
      * @method set_dirty
      */
     Notebook.prototype.set_dirty = function (value) {
         if (value === undefined) {
             value = true;
         }
         if (this.dirty == value) {
             return;
         }
         this.events.trigger('set_dirty.Notebook', {value: value});
     };
 
     /**
      * Scroll the top of the page to a given cell.
      * 
      * @method scroll_to_cell
      * @param {Number} cell_number An index of the cell to view
      * @param {Number} time Animation time in milliseconds
      * @return {Number} Pixel offset from the top of the container
      */
     Notebook.prototype.scroll_to_cell = function (cell_number, time) {
         var cells = this.get_cells();
         time = time || 0;
         cell_number = Math.min(cells.length-1,cell_number);
         cell_number = Math.max(0             ,cell_number);
         var scroll_value = cells[cell_number].element.position().top-cells[0].element.position().top ;
         this.element.animate({scrollTop:scroll_value}, time);
         return scroll_value;
     };
 
     /**
      * Scroll to the bottom of the page.
      * 
      * @method scroll_to_bottom
      */
     Notebook.prototype.scroll_to_bottom = function () {
         this.element.animate({scrollTop:this.element.get(0).scrollHeight}, 0);
     };
 
     /**
      * Scroll to the top of the page.
      * 
      * @method scroll_to_top
      */
     Notebook.prototype.scroll_to_top = function () {
         this.element.animate({scrollTop:0}, 0);
     };
 
     // Edit Notebook metadata
 
     Notebook.prototype.edit_metadata = function () {
         var that = this;
         dialog.edit_metadata({
             md: this.metadata, 
             callback: function (md) {
                 that.metadata = md;
             }, 
             name: 'Notebook',
             notebook: this,
             keyboard_manager: this.keyboard_manager});
     };
     
     Notebook.prototype.set_kernelspec_metadata = function(ks) {
         var tostore = {};
         $.map(ks, function(value, field) {
             if (field !== 'argv' && field !== 'env') {
                 tostore[field] = value;
             }
         });
         this.metadata.kernelspec = tostore;
     }
 
     // Cell indexing, retrieval, etc.
 
     /**
      * Get all cell elements in the notebook.
      * 
      * @method get_cell_elements
      * @return {jQuery} A selector of all cell elements
      */
     Notebook.prototype.get_cell_elements = function () {
         return this.container.children("div.cell");
     };
 
     /**
      * Get a particular cell element.
      * 
      * @method get_cell_element
      * @param {Number} index An index of a cell to select
      * @return {jQuery} A selector of the given cell.
      */
     Notebook.prototype.get_cell_element = function (index) {
         var result = null;
         var e = this.get_cell_elements().eq(index);
         if (e.length !== 0) {
             result = e;
         }
         return result;
     };
 
     /**
      * Try to get a particular cell by msg_id.
      * 
      * @method get_msg_cell
      * @param {String} msg_id A message UUID
      * @return {Cell} Cell or null if no cell was found.
      */
     Notebook.prototype.get_msg_cell = function (msg_id) {
         return codecell.CodeCell.msg_cells[msg_id] || null;
     };
 
     /**
      * Count the cells in this notebook.
      * 
      * @method ncells
      * @return {Number} The number of cells in this notebook
      */
     Notebook.prototype.ncells = function () {
         return this.get_cell_elements().length;
     };
 
     /**
      * Get all Cell objects in this notebook.
      * 
      * @method get_cells
      * @return {Array} This notebook's Cell objects
      */
     // TODO: we are often calling cells as cells()[i], which we should optimize
     // to cells(i) or a new method.
     Notebook.prototype.get_cells = function () {
         return this.get_cell_elements().toArray().map(function (e) {
             return $(e).data("cell");
         });
     };
 
     /**
      * Get a Cell object from this notebook.
      * 
      * @method get_cell
      * @param {Number} index An index of a cell to retrieve
      * @return {Cell} A particular cell
      */
     Notebook.prototype.get_cell = function (index) {
         var result = null;
         var ce = this.get_cell_element(index);
         if (ce !== null) {
             result = ce.data('cell');
         }
         return result;
     };
 
     /**
      * Get the cell below a given cell.
      * 
      * @method get_next_cell
      * @param {Cell} cell The provided cell
      * @return {Cell} The next cell
      */
     Notebook.prototype.get_next_cell = function (cell) {
         var result = null;
         var index = this.find_cell_index(cell);
         if (this.is_valid_cell_index(index+1)) {
             result = this.get_cell(index+1);
         }
         return result;
     };
 
     /**
      * Get the cell above a given cell.
      * 
      * @method get_prev_cell
      * @param {Cell} cell The provided cell
      * @return {Cell} The previous cell
      */
     Notebook.prototype.get_prev_cell = function (cell) {
         // TODO: off-by-one
         // nb.get_prev_cell(nb.get_cell(1)) is null
         var result = null;
         var index = this.find_cell_index(cell);
         if (index !== null && index > 1) {
             result = this.get_cell(index-1);
         }
         return result;
     };
     
     /**
      * Get the numeric index of a given cell.
      * 
      * @method find_cell_index
      * @param {Cell} cell The provided cell
      * @return {Number} The cell's numeric index
      */
     Notebook.prototype.find_cell_index = function (cell) {
         var result = null;
         this.get_cell_elements().filter(function (index) {
             if ($(this).data("cell") === cell) {
                 result = index;
             }
         });
         return result;
     };
 
     /**
      * Get a given index , or the selected index if none is provided.
      * 
      * @method index_or_selected
      * @param {Number} index A cell's index
      * @return {Number} The given index, or selected index if none is provided.
      */
     Notebook.prototype.index_or_selected = function (index) {
         var i;
         if (index === undefined || index === null) {
             i = this.get_selected_index();
             if (i === null) {
                 i = 0;
             }
         } else {
             i = index;
         }
         return i;
     };
 
     /**
      * Get the currently selected cell.
      * @method get_selected_cell
      * @return {Cell} The selected cell
      */
     Notebook.prototype.get_selected_cell = function () {
         var index = this.get_selected_index();
         return this.get_cell(index);
     };
 
     /**
      * Check whether a cell index is valid.
      * 
      * @method is_valid_cell_index
      * @param {Number} index A cell index
      * @return True if the index is valid, false otherwise
      */
     Notebook.prototype.is_valid_cell_index = function (index) {
         if (index !== null && index >= 0 && index < this.ncells()) {
             return true;
         } else {
             return false;
         }
     };
 
     /**
      * Get the index of the currently selected cell.
      
      * @method get_selected_index
      * @return {Number} The selected cell's numeric index
      */
     Notebook.prototype.get_selected_index = function () {
         var result = null;
         this.get_cell_elements().filter(function (index) {
             if ($(this).data("cell").selected === true) {
                 result = index;
             }
         });
         return result;
     };
 
 
     // Cell selection.
 
     /**
      * Programmatically select a cell.
      * 
      * @method select
      * @param {Number} index A cell's index
      * @return {Notebook} This notebook
      */
     Notebook.prototype.select = function (index) {
         if (this.is_valid_cell_index(index)) {
             var sindex = this.get_selected_index();
             if (sindex !== null && index !== sindex) {
                 // If we are about to select a different cell, make sure we are
                 // first in command mode.
                 if (this.mode !== 'command') {
                     this.command_mode();
                 }
                 this.get_cell(sindex).unselect();
             }
             var cell = this.get_cell(index);
             cell.select();
             if (cell.cell_type === 'heading') {
                 this.events.trigger('selected_cell_type_changed.Notebook',
                     {'cell_type':cell.cell_type,level:cell.level}
                 );
             } else {
                 this.events.trigger('selected_cell_type_changed.Notebook',
                     {'cell_type':cell.cell_type}
                 );
             }
         }
         return this;
     };
 
     /**
      * Programmatically select the next cell.
      *
      * @method select_next
      * @return {Notebook} This notebook
      */
     Notebook.prototype.select_next = function () {
         var index = this.get_selected_index();
         this.select(index+1);
         return this;
     };
 
     /**
      * Programmatically select the previous cell.
      *
      * @method select_prev
      * @return {Notebook} This notebook
      */
     Notebook.prototype.select_prev = function () {
         var index = this.get_selected_index();
         this.select(index-1);
         return this;
     };
 
 
     // Edit/Command mode
 
     /**
      * Gets the index of the cell that is in edit mode.
      *
      * @method get_edit_index
      *
      * @return index {int}
      **/
     Notebook.prototype.get_edit_index = function () {
         var result = null;
         this.get_cell_elements().filter(function (index) {
             if ($(this).data("cell").mode === 'edit') {
                 result = index;
             }
         });
         return result;
     };
 
     /**
      * Handle when a a cell blurs and the notebook should enter command mode.
      *
      * @method handle_command_mode
      * @param [cell] {Cell} Cell to enter command mode on.
      **/
     Notebook.prototype.handle_command_mode = function (cell) {
         if (this.mode !== 'command') {
             cell.command_mode();
             this.mode = 'command';
             this.events.trigger('command_mode.Notebook');
             this.keyboard_manager.command_mode();
         }
     };
 
     /**
      * Make the notebook enter command mode.
      *
      * @method command_mode
      **/
     Notebook.prototype.command_mode = function () {
         var cell = this.get_cell(this.get_edit_index());
         if (cell && this.mode !== 'command') {
             // We don't call cell.command_mode, but rather call cell.focus_cell()
             // which will blur and CM editor and trigger the call to
             // handle_command_mode.
             cell.focus_cell();
         }
     };
 
     /**
      * Handle when a cell fires it's edit_mode event.
      *
      * @method handle_edit_mode
      * @param [cell] {Cell} Cell to enter edit mode on.
      **/
     Notebook.prototype.handle_edit_mode = function (cell) {
         if (cell && this.mode !== 'edit') {
             cell.edit_mode();
             this.mode = 'edit';
             this.events.trigger('edit_mode.Notebook');
             this.keyboard_manager.edit_mode();
         }
     };
 
     /**
      * Make a cell enter edit mode.
      *
      * @method edit_mode
      **/
     Notebook.prototype.edit_mode = function () {
         var cell = this.get_selected_cell();
         if (cell && this.mode !== 'edit') {
             cell.unrender();
             cell.focus_editor();
         }
     };
 
     /**
      * Focus the currently selected cell.
      *
      * @method focus_cell
      **/
     Notebook.prototype.focus_cell = function () {
         var cell = this.get_selected_cell();
         if (cell === null) {return;}  // No cell is selected
         cell.focus_cell();
     };
 
     // Cell movement
 
     /**
      * Move given (or selected) cell up and select it.
      * 
      * @method move_cell_up
      * @param [index] {integer} cell index
      * @return {Notebook} This notebook
      **/
     Notebook.prototype.move_cell_up = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i) && i > 0) {
             var pivot = this.get_cell_element(i-1);
             var tomove = this.get_cell_element(i);
             if (pivot !== null && tomove !== null) {
                 tomove.detach();
                 pivot.before(tomove);
                 this.select(i-1);
                 var cell = this.get_selected_cell();
                 cell.focus_cell();
             }
             this.set_dirty(true);
         }
         return this;
     };
 
 
     /**
      * Move given (or selected) cell down and select it
      * 
      * @method move_cell_down
      * @param [index] {integer} cell index
      * @return {Notebook} This notebook
      **/
     Notebook.prototype.move_cell_down = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i) && this.is_valid_cell_index(i+1)) {
             var pivot = this.get_cell_element(i+1);
             var tomove = this.get_cell_element(i);
             if (pivot !== null && tomove !== null) {
                 tomove.detach();
                 pivot.after(tomove);
                 this.select(i+1);
                 var cell = this.get_selected_cell();
                 cell.focus_cell();
             }
         }
         this.set_dirty();
         return this;
     };
 
 
     // Insertion, deletion.
 
     /**
      * Delete a cell from the notebook.
      * 
      * @method delete_cell
      * @param [index] A cell's numeric index
      * @return {Notebook} This notebook
      */
     Notebook.prototype.delete_cell = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_selected_cell();
         this.undelete_backup = cell.toJSON();
         $('#undelete_cell').removeClass('disabled');
         if (this.is_valid_cell_index(i)) {
             var old_ncells = this.ncells();
             var ce = this.get_cell_element(i);
             ce.remove();
             if (i === 0) {
                 // Always make sure we have at least one cell.
                 if (old_ncells === 1) {
                     this.insert_cell_below('code');
                 }
                 this.select(0);
                 this.undelete_index = 0;
                 this.undelete_below = false;
             } else if (i === old_ncells-1 && i !== 0) {
                 this.select(i-1);
                 this.undelete_index = i - 1;
                 this.undelete_below = true;
             } else {
                 this.select(i);
                 this.undelete_index = i;
                 this.undelete_below = false;
             }
             this.events.trigger('delete.Cell', {'cell': cell, 'index': i});
             this.set_dirty(true);
         }
         return this;
     };
 
     /**
      * Restore the most recently deleted cell.
      * 
      * @method undelete
      */
     Notebook.prototype.undelete_cell = function() {
         if (this.undelete_backup !== null && this.undelete_index !== null) {
             var current_index = this.get_selected_index();
             if (this.undelete_index < current_index) {
                 current_index = current_index + 1;
             }
             if (this.undelete_index >= this.ncells()) {
                 this.select(this.ncells() - 1);
             }
             else {
                 this.select(this.undelete_index);
             }
             var cell_data = this.undelete_backup;
             var new_cell = null;
             if (this.undelete_below) {
                 new_cell = this.insert_cell_below(cell_data.cell_type);
             } else {
                 new_cell = this.insert_cell_above(cell_data.cell_type);
             }
             new_cell.fromJSON(cell_data);
             if (this.undelete_below) {
                 this.select(current_index+1);
             } else {
                 this.select(current_index);
             }
             this.undelete_backup = null;
             this.undelete_index = null;
         }
         $('#undelete_cell').addClass('disabled');
     };
 
     /**
      * Insert a cell so that after insertion the cell is at given index.
      *
      * If cell type is not provided, it will default to the type of the
      * currently active cell.
      *
      * Similar to insert_above, but index parameter is mandatory
      *
      * Index will be brought back into the accessible range [0,n]
      *
      * @method insert_cell_at_index
      * @param [type] {string} in ['code','markdown','heading'], defaults to 'code'
      * @param [index] {int} a valid index where to insert cell
      *
      * @return cell {cell|null} created cell or null
      **/
     Notebook.prototype.insert_cell_at_index = function(type, index){
 
         var ncells = this.ncells();
         index = Math.min(index,ncells);
         index = Math.max(index,0);
         var cell = null;
         type = type || this.get_selected_cell().cell_type;
 
         if (ncells === 0 || this.is_valid_cell_index(index) || index === ncells) {
             var cell_options = {
                 events: this.events, 
                 config: this.config, 
                 keyboard_manager: this.keyboard_manager, 
                 notebook: this,
                 tooltip: this.tooltip,
             };
             if (type === 'code') {
                 cell = new codecell.CodeCell(this.kernel, cell_options);
                 cell.set_input_prompt();
             } else if (type === 'markdown') {
                 cell = new textcell.MarkdownCell(cell_options);
             } else if (type === 'raw') {
                 cell = new textcell.RawCell(cell_options);
             } else if (type === 'heading') {
                 cell = new textcell.HeadingCell(cell_options);
             }
 
             if(this._insert_element_at_index(cell.element,index)) {
                 cell.render();
                 this.events.trigger('create.Cell', {'cell': cell, 'index': index});
                 cell.refresh();
                 // We used to select the cell after we refresh it, but there
                 // are now cases were this method is called where select is
                 // not appropriate. The selection logic should be handled by the
                 // caller of the the top level insert_cell methods.
                 this.set_dirty(true);
             }
         }
         return cell;
 
     };
 
     /**
      * Insert an element at given cell index.
      *
      * @method _insert_element_at_index
      * @param element {dom element} a cell element
      * @param [index] {int} a valid index where to inser cell
      * @private
      *
      * return true if everything whent fine.
      **/
     Notebook.prototype._insert_element_at_index = function(element, index){
         if (element === undefined){
             return false;
         }
 
         var ncells = this.ncells();
 
         if (ncells === 0) {
             // special case append if empty
             this.element.find('div.end_space').before(element);
         } else if ( ncells === index ) {
             // special case append it the end, but not empty
             this.get_cell_element(index-1).after(element);
         } else if (this.is_valid_cell_index(index)) {
             // otherwise always somewhere to append to
             this.get_cell_element(index).before(element);
         } else {
             return false;
         }
 
         if (this.undelete_index !== null && index <= this.undelete_index) {
             this.undelete_index = this.undelete_index + 1;
             this.set_dirty(true);
         }
         return true;
     };
 
     /**
      * Insert a cell of given type above given index, or at top
      * of notebook if index smaller than 0.
      *
      * default index value is the one of currently selected cell
      *
      * @method insert_cell_above
      * @param [type] {string} cell type
      * @param [index] {integer}
      *
      * @return handle to created cell or null
      **/
     Notebook.prototype.insert_cell_above = function (type, index) {
         index = this.index_or_selected(index);
         return this.insert_cell_at_index(type, index);
     };
 
     /**
      * Insert a cell of given type below given index, or at bottom
      * of notebook if index greater than number of cells
      *
      * default index value is the one of currently selected cell
      *
      * @method insert_cell_below
      * @param [type] {string} cell type
      * @param [index] {integer}
      *
      * @return handle to created cell or null
      *
      **/
     Notebook.prototype.insert_cell_below = function (type, index) {
         index = this.index_or_selected(index);
         return this.insert_cell_at_index(type, index+1);
     };
 
 
     /**
      * Insert cell at end of notebook
      *
      * @method insert_cell_at_bottom
      * @param {String} type cell type
      *
      * @return the added cell; or null
      **/
     Notebook.prototype.insert_cell_at_bottom = function (type){
         var len = this.ncells();
         return this.insert_cell_below(type,len-1);
     };
 
     /**
      * Turn a cell into a code cell.
      * 
      * @method to_code
      * @param {Number} [index] A cell's index
      */
     Notebook.prototype.to_code = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             if (!(source_cell instanceof codecell.CodeCell)) {
                 var target_cell = this.insert_cell_below('code',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 }
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.select(i);
                 var cursor = source_cell.code_mirror.getCursor();
                 target_cell.code_mirror.setCursor(cursor);
                 this.set_dirty(true);
             }
         }
     };
 
     /**
      * Turn a cell into a Markdown cell.
      * 
      * @method to_markdown
      * @param {Number} [index] A cell's index
      */
     Notebook.prototype.to_markdown = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             if (!(source_cell instanceof textcell.MarkdownCell)) {
                 var target_cell = this.insert_cell_below('markdown',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 }
                 // We must show the editor before setting its contents
                 target_cell.unrender();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.select(i);
                 if ((source_cell instanceof textcell.TextCell) && source_cell.rendered) {
                     target_cell.render();
                 }
                 var cursor = source_cell.code_mirror.getCursor();
                 target_cell.code_mirror.setCursor(cursor);
                 this.set_dirty(true);
             }
         }
     };
 
     /**
      * Turn a cell into a raw text cell.
      * 
      * @method to_raw
      * @param {Number} [index] A cell's index
      */
     Notebook.prototype.to_raw = function (index) {
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             var target_cell = null;
             if (!(source_cell instanceof textcell.RawCell)) {
                 target_cell = this.insert_cell_below('raw',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 }
                 // We must show the editor before setting its contents
                 target_cell.unrender();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.select(i);
                 var cursor = source_cell.code_mirror.getCursor();
                 target_cell.code_mirror.setCursor(cursor);
                 this.set_dirty(true);
             }
         }
     };
 
     /**
      * Turn a cell into a heading cell.
      * 
      * @method to_heading
      * @param {Number} [index] A cell's index
      * @param {Number} [level] A heading level (e.g., 1 becomes &lt;h1&gt;)
      */
     Notebook.prototype.to_heading = function (index, level) {
         level = level || 1;
         var i = this.index_or_selected(index);
         if (this.is_valid_cell_index(i)) {
             var source_element = this.get_cell_element(i);
             var source_cell = source_element.data("cell");
             var target_cell = null;
             if (source_cell instanceof textcell.HeadingCell) {
                 source_cell.set_level(level);
             } else {
                 target_cell = this.insert_cell_below('heading',i);
                 var text = source_cell.get_text();
                 if (text === source_cell.placeholder) {
                     text = '';
                 }
                 // We must show the editor before setting its contents
                 target_cell.set_level(level);
                 target_cell.unrender();
                 target_cell.set_text(text);
                 // make this value the starting point, so that we can only undo
                 // to this state, instead of a blank cell
                 target_cell.code_mirror.clearHistory();
                 source_element.remove();
                 this.select(i);
                 var cursor = source_cell.code_mirror.getCursor();
                 target_cell.code_mirror.setCursor(cursor);
                 if ((source_cell instanceof textcell.TextCell) && source_cell.rendered) {
                     target_cell.render();
                 }
             }
             this.set_dirty(true);
             this.events.trigger('selected_cell_type_changed.Notebook',
                 {'cell_type':'heading',level:level}
             );
         }
     };
 
 
     // Cut/Copy/Paste
 
     /**
      * Enable UI elements for pasting cells.
      * 
      * @method enable_paste
      */
     Notebook.prototype.enable_paste = function () {
         var that = this;
         if (!this.paste_enabled) {
             $('#paste_cell_replace').removeClass('disabled')
                 .on('click', function () {that.paste_cell_replace();});
             $('#paste_cell_above').removeClass('disabled')
                 .on('click', function () {that.paste_cell_above();});
             $('#paste_cell_below').removeClass('disabled')
                 .on('click', function () {that.paste_cell_below();});
             this.paste_enabled = true;
         }
     };
 
     /**
      * Disable UI elements for pasting cells.
      * 
      * @method disable_paste
      */
     Notebook.prototype.disable_paste = function () {
         if (this.paste_enabled) {
             $('#paste_cell_replace').addClass('disabled').off('click');
             $('#paste_cell_above').addClass('disabled').off('click');
             $('#paste_cell_below').addClass('disabled').off('click');
             this.paste_enabled = false;
         }
     };
 
     /**
      * Cut a cell.
      * 
      * @method cut_cell
      */
     Notebook.prototype.cut_cell = function () {
         this.copy_cell();
         this.delete_cell();
     };
 
     /**
      * Copy a cell.
      * 
      * @method copy_cell
      */
     Notebook.prototype.copy_cell = function () {
         var cell = this.get_selected_cell();
         this.clipboard = cell.toJSON();
         this.enable_paste();
     };
 
     /**
      * Replace the selected cell with a cell in the clipboard.
      * 
      * @method paste_cell_replace
      */
     Notebook.prototype.paste_cell_replace = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_above(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
             var old_cell = this.get_next_cell(new_cell);
             this.delete_cell(this.find_cell_index(old_cell));
             this.select(this.find_cell_index(new_cell));
         }
     };
 
     /**
      * Paste a cell from the clipboard above the selected cell.
      * 
      * @method paste_cell_above
      */
     Notebook.prototype.paste_cell_above = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_above(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
             new_cell.focus_cell();
         }
     };
 
     /**
      * Paste a cell from the clipboard below the selected cell.
      * 
      * @method paste_cell_below
      */
     Notebook.prototype.paste_cell_below = function () {
         if (this.clipboard !== null && this.paste_enabled) {
             var cell_data = this.clipboard;
             var new_cell = this.insert_cell_below(cell_data.cell_type);
             new_cell.fromJSON(cell_data);
             new_cell.focus_cell();
         }
     };
 
     // Split/merge
 
     /**
      * Split the selected cell into two, at the cursor.
      * 
      * @method split_cell
      */
     Notebook.prototype.split_cell = function () {
         var mdc = textcell.MarkdownCell;
         var rc = textcell.RawCell;
         var cell = this.get_selected_cell();
         if (cell.is_splittable()) {
             var texta = cell.get_pre_cursor();
             var textb = cell.get_post_cursor();
             cell.set_text(textb);
             var new_cell = this.insert_cell_above(cell.cell_type);
             // Unrender the new cell so we can call set_text.
             new_cell.unrender();
             new_cell.set_text(texta);
         }
     };
 
     /**
      * Combine the selected cell into the cell above it.
      * 
      * @method merge_cell_above
      */
     Notebook.prototype.merge_cell_above = function () {
         var mdc = textcell.MarkdownCell;
         var rc = textcell.RawCell;
         var index = this.get_selected_index();
         var cell = this.get_cell(index);
         var render = cell.rendered;
         if (!cell.is_mergeable()) {
             return;
         }
         if (index > 0) {
             var upper_cell = this.get_cell(index-1);
             if (!upper_cell.is_mergeable()) {
                 return;
             }
             var upper_text = upper_cell.get_text();
             var text = cell.get_text();
             if (cell instanceof codecell.CodeCell) {
                 cell.set_text(upper_text+'\n'+text);
             } else {
                 cell.unrender(); // Must unrender before we set_text.
                 cell.set_text(upper_text+'\n\n'+text);
                 if (render) {
                     // The rendered state of the final cell should match
                     // that of the original selected cell;
                     cell.render();
                 }
             }
             this.delete_cell(index-1);
             this.select(this.find_cell_index(cell));
         }
     };
 
     /**
      * Combine the selected cell into the cell below it.
      * 
      * @method merge_cell_below
      */
     Notebook.prototype.merge_cell_below = function () {
         var mdc = textcell.MarkdownCell;
         var rc = textcell.RawCell;
         var index = this.get_selected_index();
         var cell = this.get_cell(index);
         var render = cell.rendered;
         if (!cell.is_mergeable()) {
             return;
         }
         if (index < this.ncells()-1) {
             var lower_cell = this.get_cell(index+1);
             if (!lower_cell.is_mergeable()) {
                 return;
             }
             var lower_text = lower_cell.get_text();
             var text = cell.get_text();
             if (cell instanceof codecell.CodeCell) {
                 cell.set_text(text+'\n'+lower_text);
             } else {
                 cell.unrender(); // Must unrender before we set_text.
                 cell.set_text(text+'\n\n'+lower_text);
                 if (render) {
                     // The rendered state of the final cell should match
                     // that of the original selected cell;
                     cell.render();
                 }
             }
             this.delete_cell(index+1);
             this.select(this.find_cell_index(cell));
         }
     };
 
 
     // Cell collapsing and output clearing
 
     /**
      * Hide a cell's output.
      * 
      * @method collapse_output
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.collapse_output = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.collapse_output();
             this.set_dirty(true);
         }
     };
 
     /**
      * Hide each code cell's output area.
      * 
      * @method collapse_all_output
      */
     Notebook.prototype.collapse_all_output = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.collapse_output();
             }
         });
         // this should not be set if the `collapse` key is removed from nbformat
         this.set_dirty(true);
     };
 
     /**
      * Show a cell's output.
      * 
      * @method expand_output
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.expand_output = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.expand_output();
             this.set_dirty(true);
         }
     };
 
     /**
      * Expand each code cell's output area, and remove scrollbars.
      * 
      * @method expand_all_output
      */
     Notebook.prototype.expand_all_output = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.expand_output();
             }
         });
         // this should not be set if the `collapse` key is removed from nbformat
         this.set_dirty(true);
     };
 
     /**
      * Clear the selected CodeCell's output area.
      * 
      * @method clear_output
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.clear_output = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.clear_output();
             this.set_dirty(true);
         }
     };
 
     /**
      * Clear each code cell's output area.
      * 
      * @method clear_all_output
      */
     Notebook.prototype.clear_all_output = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.clear_output();
             }
         });
         this.set_dirty(true);
     };
 
     /**
      * Scroll the selected CodeCell's output area.
      * 
      * @method scroll_output
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.scroll_output = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.scroll_output();
             this.set_dirty(true);
         }
     };
 
     /**
      * Expand each code cell's output area, and add a scrollbar for long output.
      * 
      * @method scroll_all_output
      */
     Notebook.prototype.scroll_all_output = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.scroll_output();
             }
         });
         // this should not be set if the `collapse` key is removed from nbformat
         this.set_dirty(true);
     };
 
     /** Toggle whether a cell's output is collapsed or expanded.
      * 
      * @method toggle_output
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.toggle_output = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.toggle_output();
             this.set_dirty(true);
         }
     };
 
     /**
      * Hide/show the output of all cells.
      * 
      * @method toggle_all_output
      */
     Notebook.prototype.toggle_all_output = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.toggle_output();
             }
         });
         // this should not be set if the `collapse` key is removed from nbformat
         this.set_dirty(true);
     };
 
     /**
      * Toggle a scrollbar for long cell outputs.
      * 
      * @method toggle_output_scroll
      * @param {Number} index A cell's numeric index
      */
     Notebook.prototype.toggle_output_scroll = function (index) {
         var i = this.index_or_selected(index);
         var cell = this.get_cell(i);
         if (cell !== null && (cell instanceof codecell.CodeCell)) {
             cell.toggle_output_scroll();
             this.set_dirty(true);
         }
     };
 
     /**
      * Toggle the scrolling of long output on all cells.
      * 
      * @method toggle_all_output_scrolling
      */
     Notebook.prototype.toggle_all_output_scroll = function () {
         $.map(this.get_cells(), function (cell, i) {
             if (cell instanceof codecell.CodeCell) {
                 cell.toggle_output_scroll();
             }
         });
         // this should not be set if the `collapse` key is removed from nbformat
         this.set_dirty(true);
     };
 
     // Other cell functions: line numbers, ...
 
     /**
      * Toggle line numbers in the selected cell's input area.
      * 
      * @method cell_toggle_line_numbers
      */
     Notebook.prototype.cell_toggle_line_numbers = function() {
         this.get_selected_cell().toggle_line_numbers();
     };
     
     /**
      * Set the codemirror mode for all code cells, including the default for
      * new code cells.
      * 
      * @method set_codemirror_mode
      */
     Notebook.prototype.set_codemirror_mode = function(newmode){
         if (newmode === this.codemirror_mode) {
             return;
         }
         this.codemirror_mode = newmode;
         codecell.CodeCell.options_default.cm_config.mode = newmode;
         modename = newmode.name || newmode
 
         that = this;
         CodeMirror.requireMode(modename, function(){
             $.map(that.get_cells(), function(cell, i) {
                 if (cell.cell_type === 'code'){
                     cell.code_mirror.setOption('mode', newmode);
                     // This is currently redundant, because cm_config ends up as
                     // codemirror's own .options object, but I don't want to
                     // rely on that.
                     cell.cm_config.mode = newmode;
                 }
             });
         })
     };
 
     // Session related things
 
     /**
      * Start a new session and set it on each code cell.
      * 
      * @method start_session
      */
     Notebook.prototype.start_session = function (kernel_name) {
         if (kernel_name === undefined) {
             kernel_name = this.default_kernel_name;
         }
         this.session = new session.Session({
             base_url: this.base_url,
             ws_url: this.ws_url,
             notebook_path: this.notebook_path,
             notebook_name: this.notebook_name,
             // For now, create all sessions with the 'python' kernel, which is the
             // default. Later, the user will be able to select kernels. This is
             // overridden if KernelManager.kernel_cmd is specified for the server.
             kernel_name: kernel_name,
             notebook: this});
 
         this.session.start($.proxy(this._session_started, this));
     };
 
 
     /**
      * Once a session is started, link the code cells to the kernel and pass the 
      * comm manager to the widget manager
      *
      */
     Notebook.prototype._session_started = function(){
         this.kernel = this.session.kernel;
         var ncells = this.ncells();
         for (var i=0; i<ncells; i++) {
             var cell = this.get_cell(i);
             if (cell instanceof codecell.CodeCell) {
                 cell.set_kernel(this.session.kernel);
             }
         }
     };
     
     /**
      * Prompt the user to restart the IPython kernel.
      * 
      * @method restart_kernel
      */
     Notebook.prototype.restart_kernel = function () {
         var that = this;
         dialog.modal({
             notebook: this,
             keyboard_manager: this.keyboard_manager,
             title : "Restart kernel or continue running?",
             body : $("<p/>").text(
                 'Do you want to restart the current kernel?  You will lose all variables defined in it.'
             ),
             buttons : {
                 "Continue running" : {},
                 "Restart" : {
                     "class" : "btn-danger",
                     "click" : function() {
                         that.session.restart_kernel();
                     }
                 }
             }
         });
     };
     
     /**
      * Execute or render cell outputs and go into command mode.
      * 
      * @method execute_cell
      */
     Notebook.prototype.execute_cell = function () {
         // mode = shift, ctrl, alt
         var cell = this.get_selected_cell();
         var cell_index = this.find_cell_index(cell);
         
         cell.execute();
         this.command_mode();
         this.set_dirty(true);
     };
 
     /**
      * Execute or render cell outputs and insert a new cell below.
      * 
      * @method execute_cell_and_insert_below
      */
     Notebook.prototype.execute_cell_and_insert_below = function () {
         var cell = this.get_selected_cell();
         var cell_index = this.find_cell_index(cell);
         
         cell.execute();
 
         // If we are at the end always insert a new cell and return
         if (cell_index === (this.ncells()-1)) {
             this.command_mode();
             this.insert_cell_below();
             this.select(cell_index+1);
             this.edit_mode();
             this.scroll_to_bottom();
             this.set_dirty(true);
             return;
         }
 
         this.command_mode();
         this.insert_cell_below();
         this.select(cell_index+1);
         this.edit_mode();
         this.set_dirty(true);
     };
 
     /**
      * Execute or render cell outputs and select the next cell.
      * 
      * @method execute_cell_and_select_below
      */
     Notebook.prototype.execute_cell_and_select_below = function () {
 
         var cell = this.get_selected_cell();
         var cell_index = this.find_cell_index(cell);
         
         cell.execute();
 
         // If we are at the end always insert a new cell and return
         if (cell_index === (this.ncells()-1)) {
             this.command_mode();
             this.insert_cell_below();
             this.select(cell_index+1);
             this.edit_mode();
             this.scroll_to_bottom();
             this.set_dirty(true);
             return;
         }
 
         this.command_mode();
         this.select(cell_index+1);
         this.focus_cell();
         this.set_dirty(true);
     };
 
     /**
      * Execute all cells below the selected cell.
      * 
      * @method execute_cells_below
      */
     Notebook.prototype.execute_cells_below = function () {
         this.execute_cell_range(this.get_selected_index(), this.ncells());
         this.scroll_to_bottom();
     };
 
     /**
      * Execute all cells above the selected cell.
      * 
      * @method execute_cells_above
      */
     Notebook.prototype.execute_cells_above = function () {
         this.execute_cell_range(0, this.get_selected_index());
     };
 
     /**
      * Execute all cells.
      * 
      * @method execute_all_cells
      */
     Notebook.prototype.execute_all_cells = function () {
         this.execute_cell_range(0, this.ncells());
         this.scroll_to_bottom();
     };
 
     /**
      * Execute a contiguous range of cells.
      * 
      * @method execute_cell_range
      * @param {Number} start Index of the first cell to execute (inclusive)
      * @param {Number} end Index of the last cell to execute (exclusive)
      */
     Notebook.prototype.execute_cell_range = function (start, end) {
         this.command_mode();
         for (var i=start; i<end; i++) {
             this.select(i);
             this.execute_cell();
         }
     };
 
     // Persistance and loading
 
     /**
      * Getter method for this notebook's name.
      * 
      * @method get_notebook_name
      * @return {String} This notebook's name (excluding file extension)
      */
     Notebook.prototype.get_notebook_name = function () {
         var nbname = this.notebook_name.substring(0,this.notebook_name.length-6);
         return nbname;
     };
 
     /**
      * Setter method for this notebook's name.
      *
      * @method set_notebook_name
      * @param {String} name A new name for this notebook
      */
     Notebook.prototype.set_notebook_name = function (name) {
         this.notebook_name = name;
     };
 
     /**
      * Check that a notebook's name is valid.
      * 
      * @method test_notebook_name
      * @param {String} nbname A name for this notebook
      * @return {Boolean} True if the name is valid, false if invalid
      */
     Notebook.prototype.test_notebook_name = function (nbname) {
         nbname = nbname || '';
         if (nbname.length>0 && !this.notebook_name_blacklist_re.test(nbname)) {
             return true;
         } else {
             return false;
         }
     };
 
     /**
      * Load a notebook from JSON (.ipynb).
      * 
      * This currently handles one worksheet: others are deleted.
      * 
      * @method fromJSON
      * @param {Object} data JSON representation of a notebook
      */
     Notebook.prototype.fromJSON = function (data) {
         var content = data.content;
         var ncells = this.ncells();
         var i;
         for (i=0; i<ncells; i++) {
             // Always delete cell 0 as they get renumbered as they are deleted.
             this.delete_cell(0);
         }
         // Save the metadata and name.
         this.metadata = content.metadata;
         this.notebook_name = data.name;
         var trusted = true;
         
         // Trigger an event changing the kernel spec - this will set the default
         // codemirror mode
         if (this.metadata.kernelspec !== undefined) {
             this.events.trigger('spec_changed.Kernel', this.metadata.kernelspec);
         }
         
         // Only handle 1 worksheet for now.
         var worksheet = content.worksheets[0];
         if (worksheet !== undefined) {
             if (worksheet.metadata) {
                 this.worksheet_metadata = worksheet.metadata;
             }
             var new_cells = worksheet.cells;
             ncells = new_cells.length;
             var cell_data = null;
             var new_cell = null;
             for (i=0; i<ncells; i++) {
                 cell_data = new_cells[i];
                 // VERSIONHACK: plaintext -> raw
                 // handle never-released plaintext name for raw cells
                 if (cell_data.cell_type === 'plaintext'){
                     cell_data.cell_type = 'raw';
                 }
 
                 new_cell = this.insert_cell_at_index(cell_data.cell_type, i);
                 new_cell.fromJSON(cell_data);
                 if (new_cell.cell_type == 'code' && !new_cell.output_area.trusted) {
                     trusted = false;
                 }
             }
         }
         if (trusted != this.trusted) {
             this.trusted = trusted;
             this.events.trigger("trust_changed.Notebook", trusted);
         }
         if (content.worksheets.length > 1) {
             dialog.modal({
                 notebook: this,
                 keyboard_manager: this.keyboard_manager,
                 title : "Multiple worksheets",
                 body : "This notebook has " + data.worksheets.length + " worksheets, " +
                     "but this version of IPython can only handle the first.  " +
                     "If you save this notebook, worksheets after the first will be lost.",
                 buttons : {
                     OK : {
                         class : "btn-danger"
                     }
                 }
             });
         }
     };
 
     /**
      * Dump this notebook into a JSON-friendly object.
      * 
      * @method toJSON
      * @return {Object} A JSON-friendly representation of this notebook.
      */
     Notebook.prototype.toJSON = function () {
         var cells = this.get_cells();
         var ncells = cells.length;
         var cell_array = new Array(ncells);
         var trusted = true;
         for (var i=0; i<ncells; i++) {
             var cell = cells[i];
             if (cell.cell_type == 'code' && !cell.output_area.trusted) {
                 trusted = false;
             }
             cell_array[i] = cell.toJSON();
         }
         var data = {
             // Only handle 1 worksheet for now.
             worksheets : [{
                 cells: cell_array,
                 metadata: this.worksheet_metadata
             }],
             metadata : this.metadata
         };
         if (trusted != this.trusted) {
             this.trusted = trusted;
             this.events.trigger("trust_changed.Notebook", trusted);
         }
         return data;
     };
 
     /**
      * Start an autosave timer, for periodically saving the notebook.
      * 
      * @method set_autosave_interval
      * @param {Integer} interval the autosave interval in milliseconds
      */
     Notebook.prototype.set_autosave_interval = function (interval) {
         var that = this;
         // clear previous interval, so we don't get simultaneous timers
         if (this.autosave_timer) {
             clearInterval(this.autosave_timer);
         }
         
         this.autosave_interval = this.minimum_autosave_interval = interval;
         if (interval) {
             this.autosave_timer = setInterval(function() {
                 if (that.dirty) {
                     that.save_notebook();
                 }
             }, interval);
             this.events.trigger("autosave_enabled.Notebook", interval);
         } else {
             this.autosave_timer = null;
             this.events.trigger("autosave_disabled.Notebook");
         }
     };
     
     /**
      * Save this notebook on the server. This becomes a notebook instance's
      * .save_notebook method *after* the entire notebook has been loaded.
      * 
      * @method save_notebook
      */
     Notebook.prototype.save_notebook = function (extra_settings) {
         // Create a JSON model to be sent to the server.
         var model = {};
         model.name = this.notebook_name;
         model.path = this.notebook_path;
         model.type = 'notebook';
         model.format = 'json';
         model.content = this.toJSON();
         model.content.nbformat = this.nbformat;
         model.content.nbformat_minor = this.nbformat_minor;
         // time the ajax call for autosave tuning purposes.
         var start =  new Date().getTime();
         // We do the call with settings so we can set cache to false.
         var settings = {
             processData : false,
             cache : false,
             type : "PUT",
             data : JSON.stringify(model),
             headers : {'Content-Type': 'application/json'},
             success : $.proxy(this.save_notebook_success, this, start),
             error : $.proxy(this.save_notebook_error, this)
         };
         if (extra_settings) {
             for (var key in extra_settings) {
                 settings[key] = extra_settings[key];
             }
         }
         this.events.trigger('notebook_saving.Notebook');
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name
         );
         $.ajax(url, settings);
     };
     
     /**
      * Success callback for saving a notebook.
      * 
      * @method save_notebook_success
      * @param {Integer} start the time when the save request started
      * @param {Object} data JSON representation of a notebook
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.save_notebook_success = function (start, data, status, xhr) {
         this.set_dirty(false);
         this.events.trigger('notebook_saved.Notebook');
         this._update_autosave_interval(start);
         if (this._checkpoint_after_save) {
             this.create_checkpoint();
             this._checkpoint_after_save = false;
         }
     };
     
     /**
      * update the autosave interval based on how long the last save took
      * 
      * @method _update_autosave_interval
      * @param {Integer} timestamp when the save request started
      */
     Notebook.prototype._update_autosave_interval = function (start) {
         var duration = (new Date().getTime() - start);
         if (this.autosave_interval) {
             // new save interval: higher of 10x save duration or parameter (default 30 seconds)
             var interval = Math.max(10 * duration, this.minimum_autosave_interval);
             // round to 10 seconds, otherwise we will be setting a new interval too often
             interval = 10000 * Math.round(interval / 10000);
             // set new interval, if it's changed
             if (interval != this.autosave_interval) {
                 this.set_autosave_interval(interval);
             }
         }
     };
     
     /**
      * Failure callback for saving a notebook.
      * 
      * @method save_notebook_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error HTTP error message
      */
     Notebook.prototype.save_notebook_error = function (xhr, status, error) {
         this.events.trigger('notebook_save_failed.Notebook', [xhr, status, error]);
     };
 
     /**
      * Explicitly trust the output of this notebook.
      *
      * @method trust_notebook
      */
     Notebook.prototype.trust_notebook = function (extra_settings) {
         var body = $("<div>").append($("<p>")
             .text("A trusted IPython notebook may execute hidden malicious code ")
             .append($("<strong>")
                 .append(
                     $("<em>").text("when you open it")
                 )
             ).append(".").append(
                 " Selecting trust will immediately reload this notebook in a trusted state."
             ).append(
                 " For more information, see the "
             ).append($("<a>").attr("href", "http://ipython.org/ipython-doc/2/notebook/security.html")
                 .text("IPython security documentation")
             ).append(".")
         );
 
         var nb = this;
         dialog.modal({
             notebook: this,
             keyboard_manager: this.keyboard_manager,
             title: "Trust this notebook?",
             body: body,
 
             buttons: {
                 Cancel : {},
                 Trust : {
                     class : "btn-danger",
                     click : function () {
                         var cells = nb.get_cells();
                         for (var i = 0; i < cells.length; i++) {
                             var cell = cells[i];
                             if (cell.cell_type == 'code') {
                                 cell.output_area.trusted = true;
                             }
                         }
                         this.events.on('notebook_saved.Notebook', function () {
                             window.location.reload();
                         });
                         nb.save_notebook();
                     }
                 }
             }
         });
     };
 
     Notebook.prototype.new_notebook = function(){
         var path = this.notebook_path;
         var base_url = this.base_url;
         var settings = {
             processData : false,
             cache : false,
             type : "POST",
             dataType : "json",
             async : false,
             success : function (data, status, xhr){
                 var notebook_name = data.name;
                 window.open(
                     utils.url_join_encode(
                         base_url,
                         'notebooks',
                         path,
                         notebook_name
                     ),
                     '_blank'
                 );
             },
             error : utils.log_ajax_error,
         };
         var url = utils.url_join_encode(
             base_url,
             'api/contents',
             path
         );
         $.ajax(url,settings);
     };
 
 
     Notebook.prototype.copy_notebook = function(){
         var path = this.notebook_path;
         var base_url = this.base_url;
         var settings = {
             processData : false,
             cache : false,
             type : "POST",
             dataType : "json",
             data : JSON.stringify({copy_from : this.notebook_name}),
             async : false,
             success : function (data, status, xhr) {
                 window.open(utils.url_join_encode(
                     base_url,
                     'notebooks',
                     data.path,
                     data.name
                 ), '_blank');
             },
             error : utils.log_ajax_error,
         };
         var url = utils.url_join_encode(
             base_url,
             'api/contents',
             path
         );
         $.ajax(url,settings);
     };
 
     Notebook.prototype.rename = function (nbname) {
         var that = this;
         if (!nbname.match(/\.ipynb$/)) {
             nbname = nbname + ".ipynb";
         }
         var data = {name: nbname};
         var settings = {
             processData : false,
             cache : false,
             type : "PATCH",
             data : JSON.stringify(data),
             dataType: "json",
             headers : {'Content-Type': 'application/json'},
             success : $.proxy(that.rename_success, this),
             error : $.proxy(that.rename_error, this)
         };
         this.events.trigger('rename_notebook.Notebook', data);
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name
         );
         $.ajax(url, settings);
     };
 
     Notebook.prototype.delete = function () {
         var that = this;
         var settings = {
             processData : false,
             cache : false,
             type : "DELETE",
             dataType: "json",
             error : utils.log_ajax_error,
         };
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name
         );
         $.ajax(url, settings);
     };
 
     
     Notebook.prototype.rename_success = function (json, status, xhr) {
         var name = this.notebook_name = json.name;
         var path = json.path;
         this.session.rename_notebook(name, path);
         this.events.trigger('notebook_renamed.Notebook', json);
     };
 
     Notebook.prototype.rename_error = function (xhr, status, error) {
         var that = this;
         var dialog_body = $('<div/>').append(
             $("<p/>").text('This notebook name already exists.')
         );
         this.events.trigger('notebook_rename_failed.Notebook', [xhr, status, error]);
         dialog.modal({
             notebook: this,
             keyboard_manager: this.keyboard_manager,
             title: "Notebook Rename Error!",
             body: dialog_body,
             buttons : {
                 "Cancel": {},
                 "OK": {
                     class: "btn-primary",
                     click: function () {
                         this.save_widget.rename_notebook({notebook:that});
                 }}
                 },
             open : function (event, ui) {
                 var that = $(this);
                 // Upon ENTER, click the OK button.
                 that.find('input[type="text"]').keydown(function (event, ui) {
                     if (event.which === this.keyboard.keycodes.enter) {
                         that.find('.btn-primary').first().click();
                     }
                 });
                 that.find('input[type="text"]').focus();
             }
         });
     };
 
     /**
      * Request a notebook's data from the server.
      * 
      * @method load_notebook
      * @param {String} notebook_name and path A notebook to load
      */
     Notebook.prototype.load_notebook = function (notebook_name, notebook_path) {
         var that = this;
         this.notebook_name = notebook_name;
         this.notebook_path = notebook_path;
         // We do the call with settings so we can set cache to false.
         var settings = {
             processData : false,
             cache : false,
             type : "GET",
             dataType : "json",
             success : $.proxy(this.load_notebook_success,this),
             error : $.proxy(this.load_notebook_error,this),
         };
         this.events.trigger('notebook_loading.Notebook');
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name
         );
         $.ajax(url, settings);
     };
 
     /**
      * Success callback for loading a notebook from the server.
      * 
      * Load notebook data from the JSON response.
      * 
      * @method load_notebook_success
      * @param {Object} data JSON representation of a notebook
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.load_notebook_success = function (data, status, xhr) {
         this.fromJSON(data);
         if (this.ncells() === 0) {
             this.insert_cell_below('code');
             this.edit_mode(0);
         } else {
             this.select(0);
             this.handle_command_mode(this.get_cell(0));
         }
         this.set_dirty(false);
         this.scroll_to_top();
         if (data.orig_nbformat !== undefined && data.nbformat !== data.orig_nbformat) {
             var msg = "This notebook has been converted from an older " +
             "notebook format (v"+data.orig_nbformat+") to the current notebook " +
             "format (v"+data.nbformat+"). The next time you save this notebook, the " +
             "newer notebook format will be used and older versions of IPython " +
             "may not be able to read it. To keep the older version, close the " +
             "notebook without saving it.";
             dialog.modal({
                 notebook: this,
                 keyboard_manager: this.keyboard_manager,
                 title : "Notebook converted",
                 body : msg,
                 buttons : {
                     OK : {
                         class : "btn-primary"
                     }
                 }
             });
         } else if (data.orig_nbformat_minor !== undefined && data.nbformat_minor !== data.orig_nbformat_minor) {
             var that = this;
             var orig_vs = 'v' + data.nbformat + '.' + data.orig_nbformat_minor;
             var this_vs = 'v' + data.nbformat + '.' + this.nbformat_minor;
             var msg = "This notebook is version " + orig_vs + ", but we only fully support up to " +
             this_vs + ".  You can still work with this notebook, but some features " +
             "introduced in later notebook versions may not be available.";
 
             dialog.modal({
                 notebook: this,
                 keyboard_manager: this.keyboard_manager,
                 title : "Newer Notebook",
                 body : msg,
                 buttons : {
                     OK : {
                         class : "btn-danger"
                     }
                 }
             });
 
         }
         
         // Create the session after the notebook is completely loaded to prevent
         // code execution upon loading, which is a security risk.
         if (this.session === null) {
             var kernelspec = this.metadata.kernelspec || {};
             var kernel_name = kernelspec.name || this.default_kernel_name;
 
             this.start_session(kernel_name);
         }
         // load our checkpoint list
         this.list_checkpoints();
         
         // load toolbar state
         if (this.metadata.celltoolbar) {
             celltoolbar.CellToolbar.global_show();
             celltoolbar.CellToolbar.activate_preset(this.metadata.celltoolbar);
         } else {
             celltoolbar.CellToolbar.global_hide();
         }
 
         // now that we're fully loaded, it is safe to restore save functionality
         delete(this.save_notebook);
         this.events.trigger('notebook_loaded.Notebook');
     };
 
     /**
      * Failure callback for loading a notebook from the server.
      * 
      * @method load_notebook_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error HTTP error message
      */
     Notebook.prototype.load_notebook_error = function (xhr, status, error) {
         this.events.trigger('notebook_load_failed.Notebook', [xhr, status, error]);
+        utils.log_ajax_error(xhr, status, error);
         var msg;
         if (xhr.status === 400) {
-            if (xhr.responseJSON && xhr.responseJSON.message) {
-                msg = escape(xhr.responseJSON.message);
-            } else {
-                msg = escape(error);
-            }
+            msg = escape(utils.ajax_error_msg(xhr));
         } else if (xhr.status === 500) {
             msg = "An unknown error occurred while loading this notebook. " +
             "This version can load notebook formats " +
-            "v" + this.nbformat + " or earlier.";
+            "v" + this.nbformat + " or earlier. See the server log for details.";
         }
         dialog.modal({
             notebook: this,
             keyboard_manager: this.keyboard_manager,
             title: "Error loading notebook",
             body : msg,
             buttons : {
                 "OK": {}
             }
         });
     };
 
     /*********************  checkpoint-related  *********************/
     
     /**
      * Save the notebook then immediately create a checkpoint.
      * 
      * @method save_checkpoint
      */
     Notebook.prototype.save_checkpoint = function () {
         this._checkpoint_after_save = true;
         this.save_notebook();
     };
     
     /**
      * Add a checkpoint for this notebook.
      * for use as a callback from checkpoint creation.
      * 
      * @method add_checkpoint
      */
     Notebook.prototype.add_checkpoint = function (checkpoint) {
         var found = false;
         for (var i = 0; i < this.checkpoints.length; i++) {
             var existing = this.checkpoints[i];
             if (existing.id == checkpoint.id) {
                 found = true;
                 this.checkpoints[i] = checkpoint;
                 break;
             }
         }
         if (!found) {
             this.checkpoints.push(checkpoint);
         }
         this.last_checkpoint = this.checkpoints[this.checkpoints.length - 1];
     };
     
     /**
      * List checkpoints for this notebook.
      * 
      * @method list_checkpoints
      */
     Notebook.prototype.list_checkpoints = function () {
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name,
             'checkpoints'
         );
         $.get(url).done(
             $.proxy(this.list_checkpoints_success, this)
         ).fail(
             $.proxy(this.list_checkpoints_error, this)
         );
     };
 
     /**
      * Success callback for listing checkpoints.
      * 
      * @method list_checkpoint_success
      * @param {Object} data JSON representation of a checkpoint
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.list_checkpoints_success = function (data, status, xhr) {
         data = $.parseJSON(data);
         this.checkpoints = data;
         if (data.length) {
             this.last_checkpoint = data[data.length - 1];
         } else {
             this.last_checkpoint = null;
         }
         this.events.trigger('checkpoints_listed.Notebook', [data]);
     };
 
     /**
      * Failure callback for listing a checkpoint.
      * 
      * @method list_checkpoint_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error_msg HTTP error message
      */
     Notebook.prototype.list_checkpoints_error = function (xhr, status, error_msg) {
         this.events.trigger('list_checkpoints_failed.Notebook');
     };
     
     /**
      * Create a checkpoint of this notebook on the server from the most recent save.
      * 
      * @method create_checkpoint
      */
     Notebook.prototype.create_checkpoint = function () {
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name,
             'checkpoints'
         );
         $.post(url).done(
             $.proxy(this.create_checkpoint_success, this)
         ).fail(
             $.proxy(this.create_checkpoint_error, this)
         );
     };
 
     /**
      * Success callback for creating a checkpoint.
      * 
      * @method create_checkpoint_success
      * @param {Object} data JSON representation of a checkpoint
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.create_checkpoint_success = function (data, status, xhr) {
         data = $.parseJSON(data);
         this.add_checkpoint(data);
         this.events.trigger('checkpoint_created.Notebook', data);
     };
 
     /**
      * Failure callback for creating a checkpoint.
      * 
      * @method create_checkpoint_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error_msg HTTP error message
      */
     Notebook.prototype.create_checkpoint_error = function (xhr, status, error_msg) {
         this.events.trigger('checkpoint_failed.Notebook');
     };
     
     Notebook.prototype.restore_checkpoint_dialog = function (checkpoint) {
         var that = this;
         checkpoint = checkpoint || this.last_checkpoint;
         if ( ! checkpoint ) {
             console.log("restore dialog, but no checkpoint to restore to!");
             return;
         }
         var body = $('<div/>').append(
             $('<p/>').addClass("p-space").text(
                 "Are you sure you want to revert the notebook to " +
                 "the latest checkpoint?"
             ).append(
                 $("<strong/>").text(
                     " This cannot be undone."
                 )
             )
         ).append(
             $('<p/>').addClass("p-space").text("The checkpoint was last updated at:")
         ).append(
             $('<p/>').addClass("p-space").text(
                 Date(checkpoint.last_modified)
             ).css("text-align", "center")
         );
         
         dialog.modal({
             notebook: this,
             keyboard_manager: this.keyboard_manager,
             title : "Revert notebook to checkpoint",
             body : body,
             buttons : {
                 Revert : {
                     class : "btn-danger",
                     click : function () {
                         that.restore_checkpoint(checkpoint.id);
                     }
                 },
                 Cancel : {}
                 }
         });
     };
     
     /**
      * Restore the notebook to a checkpoint state.
      * 
      * @method restore_checkpoint
      * @param {String} checkpoint ID
      */
     Notebook.prototype.restore_checkpoint = function (checkpoint) {
         this.events.trigger('notebook_restoring.Notebook', checkpoint);
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name,
             'checkpoints',
             checkpoint
         );
         $.post(url).done(
             $.proxy(this.restore_checkpoint_success, this)
         ).fail(
             $.proxy(this.restore_checkpoint_error, this)
         );
     };
     
     /**
      * Success callback for restoring a notebook to a checkpoint.
      * 
      * @method restore_checkpoint_success
      * @param {Object} data (ignored, should be empty)
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.restore_checkpoint_success = function (data, status, xhr) {
         this.events.trigger('checkpoint_restored.Notebook');
         this.load_notebook(this.notebook_name, this.notebook_path);
     };
 
     /**
      * Failure callback for restoring a notebook to a checkpoint.
      * 
      * @method restore_checkpoint_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error_msg HTTP error message
      */
     Notebook.prototype.restore_checkpoint_error = function (xhr, status, error_msg) {
         this.events.trigger('checkpoint_restore_failed.Notebook');
     };
     
     /**
      * Delete a notebook checkpoint.
      * 
      * @method delete_checkpoint
      * @param {String} checkpoint ID
      */
     Notebook.prototype.delete_checkpoint = function (checkpoint) {
         this.events.trigger('notebook_restoring.Notebook', checkpoint);
         var url = utils.url_join_encode(
             this.base_url,
             'api/contents',
             this.notebook_path,
             this.notebook_name,
             'checkpoints',
             checkpoint
         );
         $.ajax(url, {
             type: 'DELETE',
             success: $.proxy(this.delete_checkpoint_success, this),
             error: $.proxy(this.delete_checkpoint_error, this)
         });
     };
     
     /**
      * Success callback for deleting a notebook checkpoint
      * 
      * @method delete_checkpoint_success
      * @param {Object} data (ignored, should be empty)
      * @param {String} status Description of response status
      * @param {jqXHR} xhr jQuery Ajax object
      */
     Notebook.prototype.delete_checkpoint_success = function (data, status, xhr) {
         this.events.trigger('checkpoint_deleted.Notebook', data);
         this.load_notebook(this.notebook_name, this.notebook_path);
     };
 
     /**
      * Failure callback for deleting a notebook checkpoint.
      * 
      * @method delete_checkpoint_error
      * @param {jqXHR} xhr jQuery Ajax object
      * @param {String} status Description of response status
      * @param {String} error HTTP error message
      */
     Notebook.prototype.delete_checkpoint_error = function (xhr, status, error) {
         this.events.trigger('checkpoint_delete_failed.Notebook', [xhr, status, error]);
     };
 
 
     // For backwards compatability.
     IPython.Notebook = Notebook;
 
     return {'Notebook': Notebook};
 });