Merge pull request #5605 from AlbertHilb/CellToolbar

Two cell toolbar fixes.

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

@@ -1,416 +1,422 b''
 //----------------------------------------------------------------------------
 //  Copyright (C) 2012  The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // CellToolbar
 //============================================================================
 
 
 /**
  * A Module to control the per-cell toolbar.
  * @module IPython
  * @namespace IPython
  * @submodule CellToolbar
  */
 var IPython = (function (IPython) {
     "use strict";
 
     /**
      * @constructor
      * @class CellToolbar
      * @param {The cell to attach the metadata UI to} cell
      */
     var CellToolbar = function (cell) {
         CellToolbar._instances.push(this);
         this.cell = cell;
         this.create_element();
         this.rebuild();
         return this;
     };
 
 
     CellToolbar.prototype.create_element = function () {
         this.inner_element = $('<div/>').addClass('celltoolbar')
         this.element = $('<div/>').addClass('ctb_hideshow')
             .append(this.inner_element);
     };
 
 
     // The default css style for the outer celltoolbar div
     // (ctb_hideshow) is display: none.
     // To show the cell toolbar, *both* of the following conditions must be met:
     // - A parent container has class `ctb_global_show`
     // - The celltoolbar has the class `ctb_show`
     // This allows global show/hide, as well as per-cell show/hide.
 
     CellToolbar.global_hide = function () {
         $('body').removeClass('ctb_global_show');
     };
 
 
     CellToolbar.global_show = function () {
         $('body').addClass('ctb_global_show');
     };
 
 
     CellToolbar.prototype.hide = function () {
         this.element.removeClass('ctb_show');
     };
 
 
     CellToolbar.prototype.show = function () {
         this.element.addClass('ctb_show');
     };
 
 
     /**
      * Class variable that should contain a dict of all available callback
      * we need to think of wether or not we allow nested namespace
      * @property _callback_dict
      * @private
      * @static
      * @type Dict
      */
     CellToolbar._callback_dict = {};
 
 
     /**
      * Class variable that should contain the reverse order list of the button
      * to add to the toolbar of each cell
      * @property _ui_controls_list
      * @private
      * @static
      * @type List
      */
     CellToolbar._ui_controls_list = [];
 
 
     /**
      * Class variable that should contain the CellToolbar instances for each
      * cell of the notebook
      *
      * @private
      * @property _instances
      * @static
      * @type List
      */
     CellToolbar._instances = [];
 
 
     /**
      * keep a list of all the available presets for the toolbar
      * @private
      * @property _presets
      * @static
      * @type Dict
      */
     CellToolbar._presets = {};
 
 
     // this is by design not a prototype.
     /**
      * Register a callback to create an UI element in a cell toolbar.
      * @method register_callback
      * @param name {String} name to use to refer to the callback. It is advised to use a prefix with the name
      * for easier sorting and avoid collision
      * @param callback {function(div, cell)} callback that will be called to generate the ui element
      * @param [cell_types] {List of String|undefined} optional list of cell types. If present the UI element
      * will be added only to cells of types in the list.
      *
      *
      * The callback will receive the following element :
      *
      *    * a div in which to add element.
      *    * the cell it is responsible from
      *
      * @example
      *
      * Example that create callback for a button that toggle between `true` and `false` label,
      * with the metadata under the key 'foo' to reflect the status of the button.
      *
      *      // first param reference to a DOM div
      *      // second param reference to the cell.
      *      var toggle =  function(div, cell) {
      *          var button_container = $(div)
      *
      *          // let's create a button that show the  current value of the metadata
      *          var button = $('<div/>').button({label:String(cell.metadata.foo)});
      *
      *          // On click, change the metadata value and update the button label
      *          button.click(function(){
      *                      var v = cell.metadata.foo;
      *                      cell.metadata.foo = !v;
      *                      button.button("option", "label", String(!v));
      *                  })
      *
      *          // add the button to the DOM div.
      *          button_container.append(button);
      *      }
      *
      *      // now we register the callback under the name `foo` to give the
      *      // user the ability to use it later
      *      CellToolbar.register_callback('foo', toggle);
      */
     CellToolbar.register_callback = function(name, callback, cell_types) {
         // Overwrite if it already exists.
         CellToolbar._callback_dict[name] = cell_types ? {callback: callback, cell_types: cell_types} : callback;
     };
 
 
     /**
      * Register a preset of UI element in a cell toolbar.
      * Not supported Yet.
      * @method register_preset
      * @param name {String} name to use to refer to the preset. It is advised to use a prefix with the name
      * for easier sorting and avoid collision
      * @param  preset_list {List of String} reverse order of the button in the toolbar. Each String of the list
      *          should correspond to a name of a registerd callback.
      *
      * @private
      * @example
      *
      *      CellToolbar.register_callback('foo.c1', function(div, cell){...});
      *      CellToolbar.register_callback('foo.c2', function(div, cell){...});
      *      CellToolbar.register_callback('foo.c3', function(div, cell){...});
      *      CellToolbar.register_callback('foo.c4', function(div, cell){...});
      *      CellToolbar.register_callback('foo.c5', function(div, cell){...});
      *
      *      CellToolbar.register_preset('foo.foo_preset1', ['foo.c1', 'foo.c2', 'foo.c5'])
      *      CellToolbar.register_preset('foo.foo_preset2', ['foo.c4', 'foo.c5'])
      */
     CellToolbar.register_preset = function(name, preset_list) {
         CellToolbar._presets[name] = preset_list;
         $([IPython.events]).trigger('preset_added.CellToolbar', {name: name});
+        // When "register_callback" is called by a custom extension, it may be executed after notebook is loaded.
+        // In that case, activate the preset if needed.
+        if (IPython.notebook && IPython.notebook.metadata && IPython.notebook.metadata.celltoolbar === name)
+            this.activate_preset(name);
     };
 
 
     /**
      * List the names of the presets that are currently registered.
      *
      * @method list_presets
      * @static
      */
     CellToolbar.list_presets = function() {
         var keys = [];
         for (var k in CellToolbar._presets) {
             keys.push(k);
         }
         return keys;
     };
 
 
     /**
      * Activate an UI preset from `register_preset`
      *
      * This does not update the selection UI.
      *
      * @method activate_preset
      * @param preset_name {String} string corresponding to the preset name
      *
      * @static
      * @private
      * @example
      *
      *      CellToolbar.activate_preset('foo.foo_preset1');
      */
     CellToolbar.activate_preset = function(preset_name){
         var preset = CellToolbar._presets[preset_name];
 
         if(preset !== undefined){
             CellToolbar._ui_controls_list = preset;
             CellToolbar.rebuild_all();
         }
+
+        $([IPython.events]).trigger('preset_activated.CellToolbar', {name: preset_name});
     };
 
 
     /**
      * This should be called on the class and not on a instance as it will trigger
      * rebuild of all the instances.
      * @method rebuild_all
      * @static
      *
      */
     CellToolbar.rebuild_all = function(){
         for(var i=0; i < CellToolbar._instances.length; i++){
             CellToolbar._instances[i].rebuild();
         }
     };
 
     /**
      * Rebuild all the button on the toolbar to update its state.
      * @method rebuild
      */
     CellToolbar.prototype.rebuild = function(){
         // strip evrything from the div
         // which is probably inner_element
         // or this.element.
         this.inner_element.empty();
         this.ui_controls_list = [];
 
         var callbacks = CellToolbar._callback_dict;
         var preset = CellToolbar._ui_controls_list;
         // Yes we iterate on the class variable, not the instance one.
         for (var i=0; i < preset.length; i++) {
             var key = preset[i];
             var callback = callbacks[key];
             if (!callback) continue;
 
             if (typeof callback === 'object') {
                 if (callback.cell_types.indexOf(this.cell.cell_type) === -1) continue;
                 callback = callback.callback;
             }
             
             var local_div = $('<div/>').addClass('button_container');
             try {
                 callback(local_div, this.cell, this);
                 this.ui_controls_list.push(key);
             } catch (e) {
                 console.log("Error in cell toolbar callback " + key, e);
                 continue;
             }
             // only append if callback succeeded.
             this.inner_element.append(local_div);
         }
 
         // If there are no controls or the cell is a rendered TextCell hide the toolbar.
         if (!this.ui_controls_list.length || (this.cell instanceof IPython.TextCell && this.cell.rendered)) {
             this.hide();
         } else {
             this.show();
         }
     };
 
 
     /**
      */
     CellToolbar.utils = {};
 
 
     /**
      * A utility function to generate bindings between a checkbox and cell/metadata
      * @method utils.checkbox_ui_generator
      * @static
      *
      * @param name {string} Label in front of the checkbox
      * @param setter {function( cell, newValue )}
      *        A setter method to set the newValue
      * @param getter {function( cell )}
      *        A getter methods which return the current value.
      *
      * @return callback {function( div, cell )} Callback to be passed to `register_callback`
      *
      * @example
      *
      * An exmple that bind the subkey `slideshow.isSectionStart` to a checkbox with a `New Slide` label
      *
      *     var newSlide = CellToolbar.utils.checkbox_ui_generator('New Slide',
      *          // setter
      *          function(cell, value){
      *              // we check that the slideshow namespace exist and create it if needed
      *              if (cell.metadata.slideshow == undefined){cell.metadata.slideshow = {}}
      *              // set the value
      *              cell.metadata.slideshow.isSectionStart = value
      *              },
      *          //geter
      *          function(cell){ var ns = cell.metadata.slideshow;
      *              // if the slideshow namespace does not exist return `undefined`
      *              // (will be interpreted as `false` by checkbox) otherwise
      *              // return the value
      *              return (ns == undefined)? undefined: ns.isSectionStart
      *              }
      *      );
      *
      *      CellToolbar.register_callback('newSlide', newSlide);
      *
      */
     CellToolbar.utils.checkbox_ui_generator = function(name, setter, getter){
         return function(div, cell, celltoolbar) {
             var button_container = $(div);
 
             var chkb = $('<input/>').attr('type', 'checkbox');
             var lbl = $('<label/>').append($('<span/>').text(name));
             lbl.append(chkb);
             chkb.attr("checked", getter(cell));
 
             chkb.click(function(){
                         var v = getter(cell);
                         setter(cell, !v);
                         chkb.attr("checked", !v);
             });
             button_container.append($('<div/>').append(lbl));
         };
     };
 
 
     /**
      * A utility function to generate bindings between a dropdown list cell
      * @method utils.select_ui_generator
      * @static
      *
      * @param list_list {list of sublist} List of sublist of metadata value and name in the dropdown list.
      *        subslit shoud contain 2 element each, first a string that woul be displayed in the dropdown list,
      *        and second the corresponding value to  be passed to setter/return by getter. the corresponding value 
      *        should not be "undefined" or behavior can be unexpected.
      * @param setter {function( cell, newValue )}
      *        A setter method to set the newValue
      * @param getter {function( cell )}
      *        A getter methods which return the current value of the metadata.
      * @param [label=""] {String} optionnal label for the dropdown menu
      *
      * @return callback {function( div, cell )} Callback to be passed to `register_callback`
      *
      * @example
      *
      *      var select_type = CellToolbar.utils.select_ui_generator([
      *              ["<None>"       , "None"      ],
      *              ["Header Slide" , "header_slide" ],
      *              ["Slide"        , "slide"        ],
      *              ["Fragment"     , "fragment"     ],
      *              ["Skip"         , "skip"         ],
      *              ],
      *              // setter
      *              function(cell, value){
      *                  // we check that the slideshow namespace exist and create it if needed
      *                  if (cell.metadata.slideshow == undefined){cell.metadata.slideshow = {}}
      *                  // set the value
      *                  cell.metadata.slideshow.slide_type = value
      *                  },
      *              //geter
      *              function(cell){ var ns = cell.metadata.slideshow;
      *                  // if the slideshow namespace does not exist return `undefined`
      *                  // (will be interpreted as `false` by checkbox) otherwise
      *                  // return the value
      *                  return (ns == undefined)? undefined: ns.slide_type
      *                  }
      *      CellToolbar.register_callback('slideshow.select', select_type);
      *
      */
     CellToolbar.utils.select_ui_generator = function(list_list, setter, getter, label) {
         label = label || "";
         return function(div, cell, celltoolbar) {
             var button_container = $(div);
             var lbl = $("<label/>").append($('<span/>').text(label));
             var select = $('<select/>').addClass('ui-widget ui-widget-content');
             for(var i=0; i < list_list.length; i++){
                 var opt = $('<option/>')
                     .attr('value', list_list[i][1])
                     .text(list_list[i][0]);
                 select.append(opt);
             }
             select.val(getter(cell));
             select.change(function(){
                         setter(cell, select.val());
                     });
             button_container.append($('<div/>').append(lbl).append(select));
         };
     };
 
 
     IPython.CellToolbar = CellToolbar;
 
     return IPython;
 }(IPython));

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

@@ -1,214 +1,219 b''
 //----------------------------------------------------------------------------
 //  Copyright (C) 2011 The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // ToolBar
 //============================================================================
 
 var IPython = (function (IPython) {
     "use strict";
 
     var MainToolBar = function (selector) {
         IPython.ToolBar.apply(this, arguments);
         this.construct();
         this.add_celltype_list();
         this.add_celltoolbar_list();
         this.bind_events();
     };
 
-    MainToolBar.prototype = new IPython.ToolBar(); 
+    MainToolBar.prototype = new IPython.ToolBar();
 
     MainToolBar.prototype.construct = function () {
         this.add_buttons_group([
                 {
                     id : 'save_b',
                     label : 'Save and Checkpoint',
                     icon : 'icon-save',
                     callback : function () {
                         IPython.notebook.save_checkpoint();
                         }
                 }
             ]);
 
         this.add_buttons_group([
                 {
                     id : 'insert_below_b',
                     label : 'Insert Cell Below',
                     icon : 'icon-plus-sign',
                     callback : function () {
                         IPython.notebook.insert_cell_below('code');
                         IPython.notebook.select_next();
                         IPython.notebook.focus_cell();
                         }
                 }
             ],'insert_above_below');
 
         this.add_buttons_group([
                 {
                     id : 'cut_b',
                     label : 'Cut Cell',
                     icon : 'icon-cut',
                     callback : function () {
                         IPython.notebook.cut_cell();
                         }
                 },
                 {
                     id : 'copy_b',
                     label : 'Copy Cell',
                     icon : 'icon-copy',
                     callback : function () {
                         IPython.notebook.copy_cell();
                         }
                 },
                 {
                     id : 'paste_b',
                     label : 'Paste Cell Below',
                     icon : 'icon-paste',
                     callback : function () {
                         IPython.notebook.paste_cell_below();
                         }
                 }
             ],'cut_copy_paste');
 
         this.add_buttons_group([
                 {
                     id : 'move_up_b',
                     label : 'Move Cell Up',
                     icon : 'icon-arrow-up',
                     callback : function () {
                         IPython.notebook.move_cell_up();
                         }
                 },
                 {
                     id : 'move_down_b',
                     label : 'Move Cell Down',
                     icon : 'icon-arrow-down',
                     callback : function () {
                         IPython.notebook.move_cell_down();
                         }
                 }
             ],'move_up_down');
-        
+
 
         this.add_buttons_group([
                 {
                     id : 'run_b',
                     label : 'Run Cell',
                     icon : 'icon-play',
                     callback : function () {
                         // emulate default shift-enter behavior
                         IPython.notebook.execute_cell_and_select_below();
                     }
                 },
                 {
                     id : 'interrupt_b',
                     label : 'Interrupt',
                     icon : 'icon-stop',
                     callback : function () {
                         IPython.notebook.session.interrupt_kernel();
                         }
                 },
                 {
                     id : 'repeat_b',
                     label : 'Restart Kernel',
                     icon : 'icon-repeat',
                     callback : function () {
                         IPython.notebook.restart_kernel();
                         }
                 }
             ],'run_int');
     };
 
     MainToolBar.prototype.add_celltype_list = function () {
         this.element
             .append($('<select/>')
                 .attr('id','cell_type')
                 // .addClass('ui-widget-content')
                 .append($('<option/>').attr('value','code').text('Code'))
                 .append($('<option/>').attr('value','markdown').text('Markdown'))
                 .append($('<option/>').attr('value','raw').text('Raw NBConvert'))
                 .append($('<option/>').attr('value','heading1').text('Heading 1'))
                 .append($('<option/>').attr('value','heading2').text('Heading 2'))
                 .append($('<option/>').attr('value','heading3').text('Heading 3'))
                 .append($('<option/>').attr('value','heading4').text('Heading 4'))
                 .append($('<option/>').attr('value','heading5').text('Heading 5'))
                 .append($('<option/>').attr('value','heading6').text('Heading 6'))
             );
     };
 
 
     MainToolBar.prototype.add_celltoolbar_list = function () {
         var label = $('<span/>').addClass("navbar-text").text('Cell Toolbar:');
         var select = $('<select/>')
             // .addClass('ui-widget-content')
             .attr('id', 'ctb_select')
             .append($('<option/>').attr('value', '').text('None'));
         this.element.append(label).append(select);
         select.change(function() {
                 var val = $(this).val()
                 if (val =='') {
                     IPython.CellToolbar.global_hide();
                     delete IPython.notebook.metadata.celltoolbar;
                 } else {
                     IPython.CellToolbar.global_show();
                     IPython.CellToolbar.activate_preset(val);
                     IPython.notebook.metadata.celltoolbar = val;
                 }
             });
         // Setup the currently registered presets.
         var presets = IPython.CellToolbar.list_presets();
         for (var i=0; i<presets.length; i++) {
             var name = presets[i];
             select.append($('<option/>').attr('value', name).text(name));
         }
         // Setup future preset registrations.
         $([IPython.events]).on('preset_added.CellToolbar', function (event, data) {
             var name = data.name;
             select.append($('<option/>').attr('value', name).text(name));
         });
+        // Update select value when a preset is activated.
+        $([IPython.events]).on('preset_activated.CellToolbar', function (event, data) {
+            if (select.val() !== data.name)
+                select.val(data.name);
+        });
     };
 
 
     MainToolBar.prototype.bind_events = function () {
         var that = this;
-        
+
         this.element.find('#cell_type').change(function () {
             var cell_type = $(this).val();
             if (cell_type === 'code') {
                 IPython.notebook.to_code();
             } else if (cell_type === 'markdown')  {
                 IPython.notebook.to_markdown();
             } else if (cell_type === 'raw')  {
                 IPython.notebook.to_raw();
             } else if (cell_type === 'heading1')  {
                 IPython.notebook.to_heading(undefined, 1);
             } else if (cell_type === 'heading2')  {
                 IPython.notebook.to_heading(undefined, 2);
             } else if (cell_type === 'heading3')  {
                 IPython.notebook.to_heading(undefined, 3);
             } else if (cell_type === 'heading4')  {
                 IPython.notebook.to_heading(undefined, 4);
             } else if (cell_type === 'heading5')  {
                 IPython.notebook.to_heading(undefined, 5);
             } else if (cell_type === 'heading6')  {
                 IPython.notebook.to_heading(undefined, 6);
             }
         });
         $([IPython.events]).on('selected_cell_type_changed.Notebook', function (event, data) {
             if (data.cell_type === 'heading') {
                 that.element.find('#cell_type').val(data.cell_type+data.level);
             } else {
                 that.element.find('#cell_type').val(data.cell_type);
             }
         });
     };
 
     IPython.MainToolBar = MainToolBar;
 
     return IPython;
 
 }(IPython));

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

@@ -1,2416 +1,2418 b''
 //----------------------------------------------------------------------------
 //  Copyright (C) 2011  The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // Notebook
 //============================================================================
 
 var IPython = (function (IPython) {
     "use strict";
 
     var utils = IPython.utils;
 
     /**
      * A notebook contains and manages cells.
      * 
      * @class Notebook
      * @constructor
      * @param {String} selector A jQuery selector for the notebook's DOM element
      * @param {Object} [options] A config object
      */
     var Notebook = function (selector, options) {
         this.options = options = options || {};
         this.base_url = options.base_url;
         this.notebook_path = options.notebook_path;
         this.notebook_name = options.notebook_name;
         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.style();
         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");
         };
     };
 
     /**
      * Tweak the notebook's CSS style.
      * 
      * @method style
      */
     Notebook.prototype.style = function () {
         $('div#notebook').addClass('border-box-sizing');
     };
 
     /**
      * 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;
 
         $([IPython.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;
         });
 
         $([IPython.events]).on('set_dirty.Notebook', function (event, data) {
             that.dirty = data.value;
         });
 
         $([IPython.events]).on('trust_changed.Notebook', function (event, data) {
             that.trusted = data.value;
         });
 
         $([IPython.events]).on('select.Cell', function (event, data) {
             var index = that.find_cell_index(data.cell);
             that.select(index);
         });
 
         $([IPython.events]).on('edit_mode.Cell', function (event, data) {
             that.handle_edit_mode(data.cell);
         });
 
         $([IPython.events]).on('command_mode.Cell', function (event, data) {
             that.handle_command_mode(data.cell);
         });
 
         $([IPython.events]).on('status_autorestarting.Kernel', function () {
             IPython.dialog.modal({
                 title: "Kernel Restarting",
                 body: "The kernel appears to have died. It will restart automatically.",
                 buttons: {
                     OK : {
                         class : "btn-primary"
                     }
                 }
             });
         });
 
         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;
         }
         $([IPython.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;
         IPython.dialog.edit_metadata(this.metadata, function (md) {
             that.metadata = md;
         }, 'Notebook');
     };
 
     // 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 IPython.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') {
                 $([IPython.events]).trigger('selected_cell_type_changed.Notebook',
                     {'cell_type':cell.cell_type,level:cell.level}
                 );
             } else {
                 $([IPython.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';
             $([IPython.events]).trigger('command_mode.Notebook');
             IPython.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';
             $([IPython.events]).trigger('edit_mode.Notebook');
             IPython.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;
             }
             $([IPython.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.
      *
      * Similar to insert_above, but index parameter is mandatory
      *
      * Index will be brought back into the accissible range [0,n]
      *
      * @method insert_cell_at_index
      * @param type {string} in ['code','markdown','heading']
      * @param [index] {int} a valid index where to inser 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;
 
         if (ncells === 0 || this.is_valid_cell_index(index) || index === ncells) {
             if (type === 'code') {
                 cell = new IPython.CodeCell(this.kernel);
                 cell.set_input_prompt();
             } else if (type === 'markdown') {
                 cell = new IPython.MarkdownCell();
             } else if (type === 'raw') {
                 cell = new IPython.RawCell();
             } else if (type === 'heading') {
                 cell = new IPython.HeadingCell();
             }
 
             if(this._insert_element_at_index(cell.element,index)) {
                 cell.render();
                 $([IPython.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 thatn number of cell
      *
      * 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 IPython.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);
                 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 IPython.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 IPython.TextCell) && source_cell.rendered) {
                     target_cell.render();
                 }
                 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 IPython.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);
                 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 IPython.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);
                 if ((source_cell instanceof IPython.TextCell) && source_cell.rendered) {
                     target_cell.render();
                 }
             }
             this.set_dirty(true);
             $([IPython.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 = IPython.MarkdownCell;
         var rc = IPython.RawCell;
         var cell = this.get_selected_cell();
         if (cell.is_splittable()) {
             var texta = cell.get_pre_cursor();
             var textb = cell.get_post_cursor();
             if (cell instanceof IPython.CodeCell) {
                 // In this case the operations keep the notebook in its existing mode
                 // so we don't need to do any post-op mode changes.
                 cell.set_text(textb);
                 var new_cell = this.insert_cell_above('code');
                 new_cell.set_text(texta);
             } else if ((cell instanceof mdc && !cell.rendered) || (cell instanceof rc)) {
                 // We know cell is !rendered so we can use set_text.
                 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 = IPython.MarkdownCell;
         var rc = IPython.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 IPython.CodeCell) {
                 cell.set_text(upper_text+'\n'+text);
             } else if ((cell instanceof mdc) || (cell instanceof rc)) {
                 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 = IPython.MarkdownCell;
         var rc = IPython.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 IPython.CodeCell) {
                 cell.set_text(text+'\n'+lower_text);
             } else if ((cell instanceof mdc) || (cell instanceof rc)) {
                 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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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 IPython.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();
     };
 
     // Session related things
 
     /**
      * Start a new session and set it on each code cell.
      * 
      * @method start_session
      */
     Notebook.prototype.start_session = function () {
         this.session = new IPython.Session(this, this.options);
         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 IPython.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;
         IPython.dialog.modal({
             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('code');
             this.select(cell_index+1);
             this.edit_mode();
             this.scroll_to_bottom();
             this.set_dirty(true);
             return;
         }
 
         this.command_mode();
         this.insert_cell_below('code');
         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('code');
             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;
         // 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;
             $([IPython.events]).trigger("trust_changed.Notebook", trusted);
         }
         if (content.worksheets.length > 1) {
             IPython.dialog.modal({
                 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;
             $([IPython.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);
             $([IPython.events]).trigger("autosave_enabled.Notebook", interval);
         } else {
             this.autosave_timer = null;
             $([IPython.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.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];
             }
         }
         $([IPython.events]).trigger('notebook_saving.Notebook');
         var url = utils.url_join_encode(
             this.base_url,
             'api/notebooks',
             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);
         $([IPython.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) {
         $([IPython.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;
         IPython.dialog.modal({
             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;
                             }
                         }
                         $([IPython.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/notebooks',
             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/notebooks',
             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)
         };
         $([IPython.events]).trigger('rename_notebook.Notebook', data);
         var url = utils.url_join_encode(
             this.base_url,
             'api/notebooks',
             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/notebooks',
             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);
         $([IPython.events]).trigger('notebook_renamed.Notebook', json);
     };
 
     Notebook.prototype.rename_error = function (xhr, status, error) {
         var that = this;
         var dialog = $('<div/>').append(
             $("<p/>").addClass("rename-message")
             .text('This notebook name already exists.')
         );
         $([IPython.events]).trigger('notebook_rename_failed.Notebook', [xhr, status, error]);
         IPython.dialog.modal({
             title: "Notebook Rename Error!",
             body: dialog,
             buttons : {
                 "Cancel": {},
                 "OK": {
                     class: "btn-primary",
                     click: function () {
                         IPython.save_widget.rename_notebook();
                 }}
                 },
             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 === IPython.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),
         };
         $([IPython.events]).trigger('notebook_loading.Notebook');
         var url = utils.url_join_encode(
             this.base_url,
             'api/notebooks',
             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.";
             IPython.dialog.modal({
                 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.";
 
             IPython.dialog.modal({
                 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) {
             this.start_session();
         }
         // load our checkpoint list
         this.list_checkpoints();
         
         // load toolbar state
         if (this.metadata.celltoolbar) {
             IPython.CellToolbar.global_show();
             IPython.CellToolbar.activate_preset(this.metadata.celltoolbar);
+        } else {
+            IPython.CellToolbar.global_hide();
         }
 
         // now that we're fully loaded, it is safe to restore save functionality
         delete(this.save_notebook);
         $([IPython.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) {
         $([IPython.events]).trigger('notebook_load_failed.Notebook', [xhr, status, error]);
         var msg;
         if (xhr.status === 400) {
             msg = error;
         } 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.";
         }
         IPython.dialog.modal({
             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/notebooks',
             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;
         }
         $([IPython.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) {
         $([IPython.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/notebooks',
             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);
         $([IPython.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) {
         $([IPython.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")
         );
         
         IPython.dialog.modal({
             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) {
         $([IPython.events]).trigger('notebook_restoring.Notebook', checkpoint);
         var url = utils.url_join_encode(
             this.base_url,
             'api/notebooks',
             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) {
         $([IPython.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) {
         $([IPython.events]).trigger('checkpoint_restore_failed.Notebook');
     };
     
     /**
      * Delete a notebook checkpoint.
      * 
      * @method delete_checkpoint
      * @param {String} checkpoint ID
      */
     Notebook.prototype.delete_checkpoint = function (checkpoint) {
         $([IPython.events]).trigger('notebook_restoring.Notebook', checkpoint);
         var url = utils.url_join_encode(
             this.base_url,
             'api/notebooks',
             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) {
         $([IPython.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_msg HTTP error message
      */
     Notebook.prototype.delete_checkpoint_error = function (xhr, status, error_msg) {
         $([IPython.events]).trigger('checkpoint_delete_failed.Notebook');
     };
 
 
     IPython.Notebook = Notebook;
 
 
     return IPython;
 
 }(IPython));