diff --git a/IPython/html/services/kernels/handlers.py b/IPython/html/services/kernels/handlers.py
index 3d4337f..b51861e 100644
--- a/IPython/html/services/kernels/handlers.py
+++ b/IPython/html/services/kernels/handlers.py
@@ -84,6 +84,9 @@ class KernelActionHandler(IPythonHandler):
 
 class ZMQChannelHandler(AuthenticatedZMQStreamHandler):
     
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, getattr(self, 'kernel_id', 'uninitialized'))
+    
     def create_stream(self):
         km = self.kernel_manager
         meth = getattr(km, 'connect_%s' % self.channel)
@@ -145,6 +148,12 @@ class ZMQChannelHandler(AuthenticatedZMQStreamHandler):
             self.zmq_stream.on_recv(self._on_zmq_reply)
 
     def on_message(self, msg):
+        if self.zmq_stream is None:
+            return
+        elif self.zmq_stream.closed():
+            self.log.info("%s closed, closing websocket.", self)
+            self.close()
+            return
         msg = json.loads(msg)
         self.session.send(self.zmq_stream, msg)
 
diff --git a/IPython/html/static/base/less/flexbox.less b/IPython/html/static/base/less/flexbox.less
index 4623833..62eaad2 100644
--- a/IPython/html/static/base/less/flexbox.less
+++ b/IPython/html/static/base/less/flexbox.less
@@ -184,6 +184,30 @@ Browsers not listed, including Safari, are supported via the styling under the
     justify-content: center;
 }
 
+.hbox.baseline, 
+.vbox.baseline,
+.baseline {
+    /* Old browsers */
+    -webkit-box-pack: baseline;
+    -moz-box-pack: baseline;
+    box-pack: baseline;
+    
+    /* Modern browsers */
+    justify-content: baseline;
+}
+
+.hbox.stretch, 
+.vbox.stretch,
+.stretch {
+    /* Old browsers */
+    -webkit-box-pack: stretch;
+    -moz-box-pack: stretch;
+    box-pack: stretch;
+    
+    /* Modern browsers */
+    justify-content: stretch;
+}
+
 .hbox.align-start, 
 .vbox.align-start,
 .align-start {
@@ -219,3 +243,27 @@ Browsers not listed, including Safari, are supported via the styling under the
     /* Modern browsers */
     align-items: center;
 }
+
+.hbox.align-baseline, 
+.vbox.align-baseline,
+.align-baseline {
+    /* Old browsers */
+    -webkit-box-align: baseline;
+    -moz-box-align: baseline;
+    box-align: baseline;
+    
+    /* Modern browsers */
+    align-items: baseline;
+}
+
+.hbox.align-stretch, 
+.vbox.align-stretch,
+.align-stretch {
+    /* Old browsers */
+    -webkit-box-align: stretch;
+    -moz-box-align: stretch;
+    box-align: stretch;
+    
+    /* Modern browsers */
+    align-items: stretch;
+}
diff --git a/IPython/html/static/notebook/js/kernelselector.js b/IPython/html/static/notebook/js/kernelselector.js
index 764db72..ce9b919 100644
--- a/IPython/html/static/notebook/js/kernelselector.js
+++ b/IPython/html/static/notebook/js/kernelselector.js
@@ -54,9 +54,19 @@ define([
             return;
         }
         var ks = this.kernelspecs[kernel_name];
+        try {
+            this.notebook.start_session(kernel_name);
+        } catch (e) {
+            if (e.name === 'SessionAlreadyStarting') {
+                console.log("Cannot change kernel while waiting for pending session start.");
+            } else {
+                // unhandled error
+                throw e;
+            }
+            // only trigger spec_changed if change was successful
+            return;
+        }
         this.events.trigger('spec_changed.Kernel', ks);
-        this.notebook.session.delete();
-        this.notebook.start_session(kernel_name);
     };
     
     KernelSelector.prototype.bind_events = function() {
diff --git a/IPython/html/static/notebook/js/menubar.js b/IPython/html/static/notebook/js/menubar.js
index a6f0b28..67e0d5b 100644
--- a/IPython/html/static/notebook/js/menubar.js
+++ b/IPython/html/static/notebook/js/menubar.js
@@ -157,12 +157,13 @@ define([
             }
         });
         this.element.find('#kill_and_exit').click(function () {
-            that.notebook.session.delete();
-            setTimeout(function(){
+            var close_window = function () {
                 // allow closing of new tabs in Chromium, impossible in FF
                 window.open('', '_self', '');
                 window.close();
-            }, 500);
+            };
+            // finish with close on success or failure
+            that.notebook.session.delete(close_window, close_window);
         });
         // Edit
         this.element.find('#cut_cell').click(function () {
diff --git a/IPython/html/static/notebook/js/notebook.js b/IPython/html/static/notebook/js/notebook.js
index e22fd51..8aaf8b4 100644
--- a/IPython/html/static/notebook/js/notebook.js
+++ b/IPython/html/static/notebook/js/notebook.js
@@ -62,6 +62,7 @@ define([
         this.save_widget = options.save_widget;
         this.tooltip = new tooltip.Tooltip(this.events);
         this.ws_url = options.ws_url;
+        this._session_starting = false;
         // default_kernel_name is a temporary measure while we implement proper
         // kernel selection and delayed start. Do not rely on it.
         this.default_kernel_name = 'python';
@@ -1525,9 +1526,38 @@ define([
      * @method start_session
      */
     Notebook.prototype.start_session = function (kernel_name) {
+        var that = this;
         if (kernel_name === undefined) {
             kernel_name = this.default_kernel_name;
         }
+        if (this._session_starting) {
+            throw new session.SessionAlreadyStarting();
+        }
+        this._session_starting = true;
+        
+        if (this.session !== null) {
+            var s = this.session;
+            this.session = null;
+            // need to start the new session in a callback after delete,
+            // because javascript does not guarantee the ordering of AJAX requests (?!)
+            s.delete(function () {
+                    // on successful delete, start new session
+                    that._session_starting = false;
+                    that.start_session(kernel_name);
+                }, function (jqXHR, status, error) {
+                    // log the failed delete, but still create a new session
+                    // 404 just means it was already deleted by someone else,
+                    // but other errors are possible.
+                    utils.log_ajax_error(jqXHR, status, error);
+                    that._session_starting = false;
+                    that.start_session(kernel_name);
+                }
+            );
+            return;
+        }
+        
+        
+    
         this.session = new session.Session({
             base_url: this.base_url,
             ws_url: this.ws_url,
@@ -1539,7 +1569,10 @@ define([
             kernel_name: kernel_name,
             notebook: this});
 
-        this.session.start($.proxy(this._session_started, this));
+        this.session.start(
+            $.proxy(this._session_started, this),
+            $.proxy(this._session_start_failed, this)
+        );
     };
 
 
@@ -1548,7 +1581,8 @@ define([
      * comm manager to the widget manager
      *
      */
-    Notebook.prototype._session_started = function(){
+    Notebook.prototype._session_started = function (){
+        this._session_starting = false;
         this.kernel = this.session.kernel;
         var ncells = this.ncells();
         for (var i=0; i<ncells; i++) {
@@ -1558,7 +1592,11 @@ define([
             }
         }
     };
-    
+    Notebook.prototype._session_start_failed = function (jqxhr, status, error){
+        this._session_starting = false;
+        utils.log_ajax_error(jqxhr, status, error);
+    };
+
     /**
      * Prompt the user to restart the IPython kernel.
      * 
diff --git a/IPython/html/static/notebook/js/notificationarea.js b/IPython/html/static/notebook/js/notificationarea.js
index 6566667..4fddb09 100644
--- a/IPython/html/static/notebook/js/notificationarea.js
+++ b/IPython/html/static/notebook/js/notificationarea.js
@@ -109,6 +109,12 @@ define([
             knw.set_message("Restarting kernel", 2000);
         });
 
+        this.events.on('status_dead.Kernel',function () {
+            that.save_widget.update_document_title();
+            knw.danger("Dead kernel");
+            $kernel_ind_icon.attr('class','kernel_dead_icon').attr('title','Kernel Dead');
+        });
+
         this.events.on('status_interrupting.Kernel',function () {
             knw.set_message("Interrupting kernel", 2000);
         });
@@ -118,6 +124,8 @@ define([
         $kernel_ind_icon.attr('class','kernel_busy_icon').attr('title','Kernel Busy');
 
         this.events.on('status_started.Kernel', function (evt, data) {
+            knw.info("Websockets Connected", 500);
+            that.events.trigger('status_busy.Kernel');
             data.kernel.kernel_info(function () {
                 that.events.trigger('status_idle.Kernel');
             });
@@ -153,8 +161,13 @@ define([
             var ws_url = data.ws_url;
             var early = data.early;
             var msg;
+
+            $kernel_ind_icon
+                .attr('class', 'kernel_disconnected_icon')
+                .attr('title', 'No Connection to Kernel');
+            
             if (!early) {
-                    knw.set_message('Reconnecting WebSockets', 1000);
+                    knw.warning('Reconnecting');
                     setTimeout(function () {
                         kernel.start_channels();
                     }, 5000);
@@ -173,7 +186,7 @@ define([
                     "OK": {},
                     "Reconnect": {
                         click: function () {
-                            knw.set_message('Reconnecting WebSockets', 1000);
+                            knw.warning('Reconnecting');
                             setTimeout(function () {
                                 kernel.start_channels();
                             }, 5000);
diff --git a/IPython/html/static/notebook/less/notificationarea.less b/IPython/html/static/notebook/less/notificationarea.less
index 022c1f3..8e34f34 100644
--- a/IPython/html/static/notebook/less/notificationarea.less
+++ b/IPython/html/static/notebook/less/notificationarea.less
@@ -43,4 +43,12 @@
     .icon(@fa-var-circle);
 }
 
+.kernel_dead_icon:before {
+    .icon(@fa-var-bomb);
+}
+
+.kernel_disconnected_icon:before {
+    .icon(@fa-var-chain-broken);
+}
+
 
diff --git a/IPython/html/static/services/kernels/js/kernel.js b/IPython/html/static/services/kernels/js/kernel.js
index b18d16d..d174e65 100644
--- a/IPython/html/static/services/kernels/js/kernel.js
+++ b/IPython/html/static/services/kernels/js/kernel.js
@@ -179,10 +179,18 @@ define([
                 that._websocket_closed(ws_host_url, false);
             }
         };
+        var ws_error = function(evt){
+            if (already_called_onclose){
+                return;
+            }
+            already_called_onclose = true;
+            that._websocket_closed(ws_host_url, false);
+        };
         var channels = [this.shell_channel, this.iopub_channel, this.stdin_channel];
         for (var i=0; i < channels.length; i++) {
             channels[i].onopen = $.proxy(this._ws_opened, this);
             channels[i].onclose = ws_closed_early;
+            channels[i].onerror = ws_error;
         }
         // switch from early-close to late-close message after 1s
         setTimeout(function() {
@@ -211,7 +219,7 @@ define([
         var channels = [this.shell_channel, this.iopub_channel, this.stdin_channel];
         for (var i=0; i < channels.length; i++) {
             // if any channel is not ready, don't trigger event.
-            if ( !channels[i].readyState ) return;
+            if ( channels[i].readyState == WebSocket.OPEN ) return;
         }
         // all events ready, trigger started event.
         this.events.trigger('status_started.Kernel', {kernel: this});
@@ -385,15 +393,17 @@ define([
     };
 
 
-    Kernel.prototype.kill = function () {
+    Kernel.prototype.kill = function (success, error) {
         if (this.running) {
             this.running = false;
             var settings = {
                 cache : false,
                 type : "DELETE",
-                error : utils.log_ajax_error,
+                success : success,
+                error : error || utils.log_ajax_error,
             };
             $.ajax(utils.url_join_encode(this.kernel_url), settings);
+            this.stop_channels();
         }
     };
 
diff --git a/IPython/html/static/services/sessions/js/session.js b/IPython/html/static/services/sessions/js/session.js
index 07339e7..14a93af 100644
--- a/IPython/html/static/services/sessions/js/session.js
+++ b/IPython/html/static/services/sessions/js/session.js
@@ -21,7 +21,7 @@ define([
         this.ws_url = options.ws_url;
     };
     
-    Session.prototype.start = function(callback) {
+    Session.prototype.start = function (success, error) {
         var that = this;
         var model = {
             notebook : {
@@ -40,11 +40,17 @@ define([
             dataType : "json",
             success : function (data, status, xhr) {
                 that._handle_start_success(data);
-                if (callback) {
-                    callback(data, status, xhr);
+                if (success) {
+                    success(data, status, xhr);
                 }
             },
-            error : utils.log_ajax_error,
+            error : function (xhr, status, err) {
+                that._handle_start_failure(xhr, status, err);
+                if (error !== undefined) {
+                    error(xhr, status, err);
+                }
+                utils.log_ajax_error(xhr, status, err);
+            }
         };
         var url = utils.url_join_encode(this.base_url, 'api/sessions');
         $.ajax(url, settings);
@@ -71,15 +77,19 @@ define([
         $.ajax(url, settings);
     };
     
-    Session.prototype.delete = function() {
+    Session.prototype.delete = function (success, error) {
         var settings = {
             processData : false,
             cache : false,
             type : "DELETE",
             dataType : "json",
-            error : utils.log_ajax_error,
+            success : success,
+            error : error || utils.log_ajax_error,
         };
-        this.kernel.running = false;
+        if (this.kernel) {
+            this.kernel.running = false;
+            this.kernel.stop_channels();
+        }
         var url = utils.url_join_encode(this.base_url, 'api/sessions', this.id);
         $.ajax(url, settings);
     };
@@ -99,6 +109,11 @@ define([
         this.kernel = new kernel.Kernel(kernel_service_url, this.ws_url, this.notebook, this.kernel_name);
         this.kernel._kernel_started(data.kernel);
     };
+
+    Session.prototype._handle_start_failure = function (xhr, status, error) {
+        this.events.trigger('start_failed.Session', [this, xhr, status, error]);
+        this.events.trigger('status_dead.Kernel');
+    };
     
     /**
      * Prompt the user to restart the IPython kernel.
@@ -118,8 +133,18 @@ define([
         this.kernel.kill();
     };
     
+    var SessionAlreadyStarting = function (message) {
+        this.name = "SessionAlreadyStarting";
+        this.message = (message || "");
+    };
+    
+    SessionAlreadyStarting.prototype = Error.prototype;
+    
     // For backwards compatability.
     IPython.Session = Session;
 
-    return {'Session': Session};
+    return {
+        Session: Session,
+        SessionAlreadyStarting: SessionAlreadyStarting,
+    };
 });
diff --git a/IPython/html/static/style/ipython.min.css b/IPython/html/static/style/ipython.min.css
index 158f463..f5a42c9 100644
--- a/IPython/html/static/style/ipython.min.css
+++ b/IPython/html/static/style/ipython.min.css
@@ -1501,7 +1501,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -1532,7 +1532,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -1584,7 +1584,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -1639,7 +1639,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -1691,7 +1691,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -1724,7 +1724,7 @@ div.cell.text_cell.rendered {
   width: 30px;
 }
 .widget-modal {
-  /* ContainerWidget - ModalView */
+  /* Box - ModalView */
   overflow: hidden;
   position: absolute !important;
   top: 0px;
@@ -1732,11 +1732,11 @@ div.cell.text_cell.rendered {
   margin-left: 0px !important;
 }
 .widget-modal-body {
-  /* ContainerWidget - ModalView Body */
+  /* Box - ModalView Body */
   max-height: none !important;
 }
-.widget-container {
-  /* ContainerWidget */
+.widget-box {
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
diff --git a/IPython/html/static/style/style.min.css b/IPython/html/static/style/style.min.css
index 473f26e..77a2e26 100644
--- a/IPython/html/static/style/style.min.css
+++ b/IPython/html/static/style/style.min.css
@@ -9273,7 +9273,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -9304,7 +9304,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -9356,7 +9356,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -9411,7 +9411,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -9463,7 +9463,7 @@ div.cell.text_cell.rendered {
   box-pack: start;
   /* Modern browsers */
   justify-content: flex-start;
-  /* ContainerWidget */
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -9496,7 +9496,7 @@ div.cell.text_cell.rendered {
   width: 30px;
 }
 .widget-modal {
-  /* ContainerWidget - ModalView */
+  /* Box - ModalView */
   overflow: hidden;
   position: absolute !important;
   top: 0px;
@@ -9504,11 +9504,11 @@ div.cell.text_cell.rendered {
   margin-left: 0px !important;
 }
 .widget-modal-body {
-  /* ContainerWidget - ModalView Body */
+  /* Box - ModalView Body */
   max-height: none !important;
 }
-.widget-container {
-  /* ContainerWidget */
+.widget-box {
+  /* Box */
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
@@ -10006,6 +10006,38 @@ ul#help_menu li a i {
 .kernel_busy_icon:before.pull-right {
   margin-left: .3em;
 }
+.kernel_dead_icon:before {
+  display: inline-block;
+  font-family: FontAwesome;
+  font-style: normal;
+  font-weight: normal;
+  line-height: 1;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  content: "\f1e2";
+}
+.kernel_dead_icon:before.pull-left {
+  margin-right: .3em;
+}
+.kernel_dead_icon:before.pull-right {
+  margin-left: .3em;
+}
+.kernel_disconnected_icon:before {
+  display: inline-block;
+  font-family: FontAwesome;
+  font-style: normal;
+  font-weight: normal;
+  line-height: 1;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  content: "\f127";
+}
+.kernel_disconnected_icon:before.pull-left {
+  margin-right: .3em;
+}
+.kernel_disconnected_icon:before.pull-right {
+  margin-left: .3em;
+}
 .notification_widget {
   color: #777777;
   padding: 1px 12px;
diff --git a/IPython/html/static/widgets/js/init.js b/IPython/html/static/widgets/js/init.js
index 1d92668..cfbd134 100644
--- a/IPython/html/static/widgets/js/init.js
+++ b/IPython/html/static/widgets/js/init.js
@@ -5,7 +5,7 @@ define([
     "widgets/js/manager",
     "widgets/js/widget_bool",
     "widgets/js/widget_button",
-    "widgets/js/widget_container",
+    "widgets/js/widget_box",
     "widgets/js/widget_float",
     "widgets/js/widget_image",
     "widgets/js/widget_int",
diff --git a/IPython/html/static/widgets/js/widget_container.js b/IPython/html/static/widgets/js/widget_box.js
similarity index 76%
rename from IPython/html/static/widgets/js/widget_container.js
rename to IPython/html/static/widgets/js/widget_box.js
index e568733..a1e97fe 100644
--- a/IPython/html/static/widgets/js/widget_container.js
+++ b/IPython/html/static/widgets/js/widget_box.js
@@ -7,11 +7,10 @@ define([
     "bootstrap",
 ], function(widget, $){
 
-    var ContainerView = widget.DOMWidgetView.extend({
+    var BoxView = widget.DOMWidgetView.extend({
         initialize: function(){
             // Public constructor
-            ContainerView.__super__.initialize.apply(this, arguments);
-            this.update_children([], this.model.get('children'));
+            BoxView.__super__.initialize.apply(this, arguments);
             this.model.on('change:children', function(model, value) {
                 this.update_children(model.previous('children'), value);
             }, this);
@@ -19,7 +18,9 @@ define([
 
         render: function(){
             // Called when view is rendered.
-            this.$el.addClass('widget-container').addClass('vbox');
+            this.$box = this.$el;
+            this.$box.addClass('widget-box');
+            this.update_children([], this.model.get('children'));
         },
         
         update_children: function(old_list, new_list) {
@@ -37,7 +38,7 @@ define([
         add_child_model: function(model) {
             // Called when a model is added to the children list.
             var view = this.create_child_view(model);
-            this.$el.append(view.$el);
+            this.$box.append(view.$el);
 
             // Trigger the displayed event of the child view.
             this.after_displayed(function() {
@@ -45,9 +46,54 @@ define([
             });
         },
     });
-    
 
-    var PopupView = widget.DOMWidgetView.extend({
+
+    var FlexBoxView = BoxView.extend({
+        render: function(){
+            FlexBoxView.__super__.render.apply(this);
+            this.model.on('change:orientation', this.update_orientation, this);
+            this.model.on('change:flex', this._flex_changed, this);
+            this.model.on('change:pack', this._pack_changed, this);
+            this.model.on('change:align', this._align_changed, this);
+            this._flex_changed();
+            this._pack_changed();
+            this._align_changed();
+            this.update_orientation();
+        },
+
+        update_orientation: function(){
+            var orientation = this.model.get("orientation");
+            if (orientation == "vertical") {
+                this.$box.removeClass("hbox").addClass("vbox");
+            } else {
+                this.$box.removeClass("vbox").addClass("hbox");
+            }
+        },
+
+        _flex_changed: function(){
+            if (this.model.previous('flex')) {
+                this.$box.removeClass('box-flex' + this.model.previous('flex'));
+            }
+            this.$box.addClass('box-flex' + this.model.get('flex'));
+        },
+
+        _pack_changed: function(){
+            if (this.model.previous('pack')) {
+                this.$box.removeClass(this.model.previous('pack'));
+            }
+            this.$box.addClass(this.model.get('pack'));
+        },
+
+        _align_changed: function(){
+            if (this.model.previous('align')) {
+                this.$box.removeClass('align-' + this.model.previous('align'));
+            }
+            this.$box.addClass('align-' + this.model.get('align'));
+        },
+    });
+
+    var PopupView = BoxView.extend({
+
         render: function(){
             // Called when view is rendered.
             var that = this;
@@ -130,11 +176,11 @@ define([
             this.$title = $('<div />')
                 .addClass('widget-modal-title')
                 .html("&nbsp;")
-                .appendTo(this.$title_bar);
-            this.$body = $('<div />')
+                .appendTo(this.$title_bar);     
+            this.$box = $('<div />')
                 .addClass('modal-body')
                 .addClass('widget-modal-body')
-                .addClass('widget-container')
+                .addClass('widget-box')
                 .addClass('vbox')
                 .appendTo(this.$window);
             
@@ -149,7 +195,7 @@ define([
             this.$window.draggable({handle: '.popover-title', snap: '#notebook, .modal', snapMode: 'both'});
             this.$window.resizable();
             this.$window.on('resize', function(){
-                that.$body.outerHeight(that.$window.innerHeight() - that.$title_bar.outerHeight());
+                that.$box.outerHeight(that.$window.innerHeight() - that.$title_bar.outerHeight());
             });
 
             this._shown_once = false;
@@ -203,29 +249,6 @@ define([
             this.$window.css('z-index', max_zindex);
         },
         
-        update_children: function(old_list, new_list) {
-            // Called when the children list is modified.
-            this.do_diff(old_list, new_list, 
-                $.proxy(this.remove_child_model, this),
-                $.proxy(this.add_child_model, this));
-        },
-
-        remove_child_model: function(model) {
-            // Called when a child is removed from children list.
-            this.pop_child_view(model).remove();
-        },
-
-        add_child_model: function(model) {
-            // Called when a child is added to children list.
-            var view = this.create_child_view(model);
-            this.$body.append(view.$el);
-
-            // Trigger the displayed event of the child view.
-            this.after_displayed(function() {
-                view.trigger('displayed');
-            });
-        },
-        
         update: function(){
             // Update the contents of this view
             //
@@ -277,7 +300,8 @@ define([
     });
 
     return {
-        'ContainerView': ContainerView,
+        'BoxView': BoxView,
         'PopupView': PopupView,
+        'FlexBoxView': FlexBoxView,
     };
 });
diff --git a/IPython/html/static/widgets/less/widgets.less b/IPython/html/static/widgets/less/widgets.less
index 28996f6..c26aa27 100644
--- a/IPython/html/static/widgets/less/widgets.less
+++ b/IPython/html/static/widgets/less/widgets.less
@@ -226,7 +226,7 @@
     margin : 5px;
 
     .start();
-    .widget-container();
+    .widget-box();
 }
 
 .widget-hbox {
@@ -258,7 +258,7 @@
 }
 
 .widget-modal {
-    /* ContainerWidget - ModalView */   
+    /* Box - ModalView */   
     overflow    : hidden; 
     position    : absolute !important;
     top         : 0px; 
@@ -267,12 +267,12 @@
 }
 
 .widget-modal-body {
-    /* ContainerWidget - ModalView Body */
+    /* Box - ModalView Body */
     max-height: none !important;
 }
 
-.widget-container {
-    /* ContainerWidget */
+.widget-box {
+    /* Box */
     .border-box-sizing();
     .align-start();
 }
diff --git a/IPython/html/tests/services/kernel.js b/IPython/html/tests/services/kernel.js
index bcbda9e..4ff1eee 100644
--- a/IPython/html/tests/services/kernel.js
+++ b/IPython/html/tests/services/kernel.js
@@ -1,12 +1,12 @@
 
 //
-// Miscellaneous javascript tests
+// Kernel tests
 //
 casper.notebook_test(function () {
     this.evaluate(function () {
         IPython.notebook.kernel.kernel_info(
             function(msg){
-                    IPython._kernel_info_response = msg;
+                IPython._kernel_info_response = msg;
             })
     });
 
@@ -24,5 +24,41 @@ casper.notebook_test(function () {
         this.test.assertTrue( kernel_info_response.msg_type === 'kernel_info_reply', 'Kernel info request return kernel_info_reply');
         this.test.assertTrue( kernel_info_response.content !== undefined, 'Kernel_info_reply is not undefined');
     });
-
+    
+    this.thenEvaluate(function () {
+        var kernel = IPython.notebook.session.kernel;
+        IPython._channels = [
+            kernel.shell_channel,
+            kernel.iopub_channel,
+            kernel.stdin_channel
+        ];
+        kernel.kill();
+    });
+    
+    this.waitFor(function () {
+        return this.evaluate(function(){
+            for (var i=0; i < IPython._channels.length; i++) {
+                var ws = IPython._channels[i];
+                if (ws.readyState !== ws.CLOSED) {
+                    return false;
+                }
+            }
+            return true;
+        });
+    });
+    
+    this.then(function () {
+        var states = this.evaluate(function() {
+            var states = [];
+            for (var i = 0; i < IPython._channels.length; i++) {
+                states.push(IPython._channels[i].readyState);
+            }
+            return states;
+        });
+        
+        for (var i = 0; i < states.length; i++) {
+            this.test.assertEquals(states[i], WebSocket.CLOSED,
+                "Kernel.kill closes websockets[" + i + "]");
+        }
+    });
 });
diff --git a/IPython/html/tests/services/session.js b/IPython/html/tests/services/session.js
new file mode 100644
index 0000000..af066cf
--- /dev/null
+++ b/IPython/html/tests/services/session.js
@@ -0,0 +1,43 @@
+
+//
+// Tests for the Session object
+//
+
+casper.notebook_test(function () {
+    this.evaluate(function () {
+        var kernel = IPython.notebook.session.kernel;
+        IPython._channels = [
+            kernel.shell_channel,
+            kernel.iopub_channel,
+            kernel.stdin_channel
+        ];
+        IPython.notebook.session.delete();
+    });
+    
+    this.waitFor(function () {
+        return this.evaluate(function(){
+            for (var i=0; i < IPython._channels.length; i++) {
+                var ws = IPython._channels[i];
+                if (ws.readyState !== ws.CLOSED) {
+                    return false;
+                }
+            }
+            return true;
+        });
+    });
+
+    this.then(function () {
+        var states = this.evaluate(function() {
+            var states = [];
+            for (var i = 0; i < IPython._channels.length; i++) {
+                states.push(IPython._channels[i].readyState);
+            }
+            return states;
+        });
+        
+        for (var i = 0; i < states.length; i++) {
+            this.test.assertEquals(states[i], WebSocket.CLOSED,
+                "Session.delete closes websockets[" + i + "]");
+        }
+    });
+});
diff --git a/IPython/html/tests/widgets/widget.js b/IPython/html/tests/widgets/widget.js
index 787b0f2..005d75e 100644
--- a/IPython/html/tests/widgets/widget.js
+++ b/IPython/html/tests/widgets/widget.js
@@ -147,7 +147,7 @@ casper.notebook_test(function () {
     var textbox = {};
     throttle_index = this.append_cell(
         'import time\n' +
-        'textbox = widgets.TextWidget()\n' +
+        'textbox = widgets.Text()\n' +
         'display(textbox)\n' +
         'textbox.add_class("my-throttle-textbox", selector="input")\n' +
         'def handle_change(name, old, new):\n' +
diff --git a/IPython/html/tests/widgets/widget_bool.js b/IPython/html/tests/widgets/widget_bool.js
index 4fd1007..0fe80b9 100644
--- a/IPython/html/tests/widgets/widget_bool.js
+++ b/IPython/html/tests/widgets/widget_bool.js
@@ -7,8 +7,8 @@ casper.notebook_test(function () {
     this.execute_cell_then(index);
 
     var bool_index = this.append_cell(
-        'bool_widgets = [widgets.CheckboxWidget(description="Title", value=True),\n' +
-        '    widgets.ToggleButtonWidget(description="Title", value=True)]\n' +
+        'bool_widgets = [widgets.Checkbox(description="Title", value=True),\n' +
+        '    widgets.ToggleButton(description="Title", value=True)]\n' +
         'display(bool_widgets[0])\n' +
         'display(bool_widgets[1])\n' +
         'print("Success")');
diff --git a/IPython/html/tests/widgets/widget_container.js b/IPython/html/tests/widgets/widget_box.js
similarity index 93%
rename from IPython/html/tests/widgets/widget_container.js
rename to IPython/html/tests/widgets/widget_box.js
index e3faa75..c1b422a 100644
--- a/IPython/html/tests/widgets/widget_container.js
+++ b/IPython/html/tests/widgets/widget_box.js
@@ -7,8 +7,8 @@ casper.notebook_test(function () {
     this.execute_cell_then(index);
 
     var container_index = this.append_cell(
-        'container = widgets.ContainerWidget()\n' +
-        'button = widgets.ButtonWidget()\n'+
+        'container = widgets.Box()\n' +
+        'button = widgets.Button()\n'+
         'container.children = [button]\n'+
         'display(container)\n'+
         'container.add_class("my-test-class")\n'+
@@ -23,7 +23,7 @@ casper.notebook_test(function () {
             'Widget subarea exists.');
 
         this.test.assert(this.cell_element_exists(index, 
-            '.widget-area .widget-subarea .widget-container'),
+            '.widget-area .widget-subarea .widget-box'),
             'Widget container exists.');
 
         this.test.assert(this.cell_element_exists(index, 
@@ -70,7 +70,7 @@ casper.notebook_test(function () {
             'Display container child executed with correct output.');
 
         this.test.assert(! this.cell_element_exists(index, 
-            '.widget-area .widget-subarea .widget-container'),
+            '.widget-area .widget-subarea .widget-box'),
             'Parent container not displayed.');
 
         this.test.assert(this.cell_element_exists(index, 
diff --git a/IPython/html/tests/widgets/widget_button.js b/IPython/html/tests/widgets/widget_button.js
index ae0aec6..304f64d 100644
--- a/IPython/html/tests/widgets/widget_button.js
+++ b/IPython/html/tests/widgets/widget_button.js
@@ -7,7 +7,7 @@ casper.notebook_test(function () {
     this.execute_cell_then(index);
 
     var button_index = this.append_cell(
-        'button = widgets.ButtonWidget(description="Title")\n' +
+        'button = widgets.Button(description="Title")\n' +
         'display(button)\n' +
         'print("Success")\n' +
         'def handle_click(sender):\n' +
diff --git a/IPython/html/tests/widgets/widget_float.js b/IPython/html/tests/widgets/widget_float.js
index a26c42d..a2f4e74 100644
--- a/IPython/html/tests/widgets/widget_float.js
+++ b/IPython/html/tests/widgets/widget_float.js
@@ -9,7 +9,7 @@ casper.notebook_test(function () {
     var float_text = {};
     float_text.query = '.widget-area .widget-subarea .widget-hbox-single .my-second-float-text';
     float_text.index = this.append_cell(
-        'float_widget = widgets.FloatTextWidget()\n' +
+        'float_widget = widgets.FloatText()\n' +
         'display(float_widget)\n' + 
         'float_widget.add_class("my-second-float-text", selector="input")\n' + 
         'print(float_widget.model_id)\n');
@@ -59,8 +59,8 @@ casper.notebook_test(function () {
     var slider = {};
     slider.query = '.widget-area .widget-subarea .widget-hbox-single .slider';
     slider.index = this.append_cell(
-        'floatrange = [widgets.BoundedFloatTextWidget(), \n' +
-        '    widgets.FloatSliderWidget()]\n' +
+        'floatrange = [widgets.BoundedFloatText(), \n' +
+        '    widgets.FloatSlider()]\n' +
         '[display(floatrange[i]) for i in range(2)]\n' + 
         'print("Success")\n');
     this.execute_cell_then(slider.index, function(index){
diff --git a/IPython/html/tests/widgets/widget_image.js b/IPython/html/tests/widgets/widget_image.js
index 04b1451..c858c68 100644
--- a/IPython/html/tests/widgets/widget_image.js
+++ b/IPython/html/tests/widgets/widget_image.js
@@ -18,7 +18,7 @@ casper.notebook_test(function () {
     var image_index = this.append_cell(
         'import base64\n' + 
         'data = base64.b64decode("' + test_jpg + '")\n' +
-        'image = widgets.ImageWidget()\n' +
+        'image = widgets.Image()\n' +
         'image.format = "jpeg"\n' +
         'image.value = data\n' +
         'image.width = "50px"\n' +
diff --git a/IPython/html/tests/widgets/widget_int.js b/IPython/html/tests/widgets/widget_int.js
index 4393664..a9bc43d 100644
--- a/IPython/html/tests/widgets/widget_int.js
+++ b/IPython/html/tests/widgets/widget_int.js
@@ -9,7 +9,7 @@ casper.notebook_test(function () {
     var int_text = {};
     int_text.query = '.widget-area .widget-subarea .widget-hbox-single .my-second-int-text';
     int_text.index = this.append_cell(
-        'int_widget = widgets.IntTextWidget()\n' +
+        'int_widget = widgets.IntText()\n' +
         'display(int_widget)\n' + 
         'int_widget.add_class("my-second-int-text", selector="input")\n' + 
         'print(int_widget.model_id)\n');
diff --git a/IPython/html/tests/widgets/widget_selection.js b/IPython/html/tests/widgets/widget_selection.js
index 25d5b86..dac47e0 100644
--- a/IPython/html/tests/widgets/widget_selection.js
+++ b/IPython/html/tests/widgets/widget_selection.js
@@ -44,10 +44,10 @@ casper.notebook_test(function () {
 //values=["' + selection_values + '"[i] for i in range(4)]
     selection_index = this.append_cell(
         'values=["' + selection_values + '"[i] for i in range(4)]\n' +
-        'selection = [widgets.DropdownWidget(values=values),\n' +
-        '    widgets.ToggleButtonsWidget(values=values),\n' +
-        '    widgets.RadioButtonsWidget(values=values),\n' +
-        '    widgets.SelectWidget(values=values)]\n' +
+        'selection = [widgets.Dropdown(values=values),\n' +
+        '    widgets.ToggleButtons(values=values),\n' +
+        '    widgets.RadioButtons(values=values),\n' +
+        '    widgets.Select(values=values)]\n' +
         '[display(selection[i]) for i in range(4)]\n' +
         'for widget in selection:\n' +
         '    def handle_change(name,old,new):\n' +
diff --git a/IPython/html/tests/widgets/widget_selectioncontainer.js b/IPython/html/tests/widgets/widget_selectioncontainer.js
index 1cc9526..57e9bd1 100644
--- a/IPython/html/tests/widgets/widget_selectioncontainer.js
+++ b/IPython/html/tests/widgets/widget_selectioncontainer.js
@@ -9,10 +9,10 @@ casper.notebook_test(function () {
     // Test tab view
     var multicontainer1_query = '.widget-area .widget-subarea div div.nav-tabs';
     var multicontainer1_index = this.append_cell(
-        'multicontainer = widgets.TabWidget()\n' +
-        'page1 = widgets.TextWidget()\n' +
-        'page2 = widgets.TextWidget()\n' +
-        'page3 = widgets.TextWidget()\n' +
+        'multicontainer = widgets.Tab()\n' +
+        'page1 = widgets.Text()\n' +
+        'page2 = widgets.Text()\n' +
+        'page3 = widgets.Text()\n' +
         'multicontainer.children = [page1, page2, page3]\n' +
         'display(multicontainer)\n' +
         'multicontainer.selected_index = 0\n' +
@@ -64,10 +64,10 @@ casper.notebook_test(function () {
     // Test accordion view
     var multicontainer2_query = '.widget-area .widget-subarea .panel-group';
     var multicontainer2_index = this.append_cell(
-        'multicontainer = widgets.AccordionWidget()\n' +
-        'page1 = widgets.TextWidget()\n' +
-        'page2 = widgets.TextWidget()\n' +
-        'page3 = widgets.TextWidget()\n' +
+        'multicontainer = widgets.Accordion()\n' +
+        'page1 = widgets.Text()\n' +
+        'page2 = widgets.Text()\n' +
+        'page3 = widgets.Text()\n' +
         'multicontainer.children = [page1, page2, page3]\n' +
         'multicontainer.set_title(2, "good")\n' +
         'display(multicontainer)\n' +
diff --git a/IPython/html/tests/widgets/widget_string.js b/IPython/html/tests/widgets/widget_string.js
index 1288cbd..8e9acee 100644
--- a/IPython/html/tests/widgets/widget_string.js
+++ b/IPython/html/tests/widgets/widget_string.js
@@ -7,10 +7,10 @@ casper.notebook_test(function () {
     this.execute_cell_then(index);
 
     var string_index = this.append_cell(
-        'string_widget = [widgets.TextWidget(value = "xyz", placeholder = "abc"),\n' +
-        '    widgets.TextareaWidget(value = "xyz", placeholder = "def"),\n' +
-        '    widgets.HTMLWidget(value = "xyz"),\n' +
-        '    widgets.LatexWidget(value = "$\\\\LaTeX{}$")]\n' +
+        'string_widget = [widgets.Text(value = "xyz", placeholder = "abc"),\n' +
+        '    widgets.Textarea(value = "xyz", placeholder = "def"),\n' +
+        '    widgets.HTML(value = "xyz"),\n' +
+        '    widgets.Latex(value = "$\\\\LaTeX{}$")]\n' +
         '[display(widget) for widget in string_widget]\n'+
         'print("Success")');
     this.execute_cell_then(string_index, function(index){
diff --git a/IPython/html/widgets/__init__.py b/IPython/html/widgets/__init__.py
index c0b3d2a..d3cdb11 100644
--- a/IPython/html/widgets/__init__.py
+++ b/IPython/html/widgets/__init__.py
@@ -1,12 +1,23 @@
 from .widget import Widget, DOMWidget, CallbackDispatcher
 
+from .widget_bool import Checkbox, ToggleButton
+from .widget_button import Button
+from .widget_box import Box, Popup, FlexBox, HBox, VBox
+from .widget_float import FloatText, BoundedFloatText, FloatSlider, FloatProgress, FloatRangeSlider
+from .widget_image import Image
+from .widget_int import IntText, BoundedIntText, IntSlider, IntProgress, IntRangeSlider
+from .widget_selection import RadioButtons, ToggleButtons, Dropdown, Select
+from .widget_selectioncontainer import Tab, Accordion
+from .widget_string import HTML, Latex, Text, Textarea
+from .interaction import interact, interactive, fixed
+
+# Deprecated classes
 from .widget_bool import CheckboxWidget, ToggleButtonWidget
 from .widget_button import ButtonWidget
-from .widget_container import ContainerWidget, PopupWidget
-from .widget_float import FloatTextWidget, BoundedFloatTextWidget, FloatSliderWidget, FloatProgressWidget, FloatRangeSliderWidget
+from .widget_box import ContainerWidget, PopupWidget
+from .widget_float import FloatTextWidget, BoundedFloatTextWidget, FloatSliderWidget, FloatProgressWidget
 from .widget_image import ImageWidget
-from .widget_int import IntTextWidget, BoundedIntTextWidget, IntSliderWidget, IntProgressWidget, IntRangeSliderWidget
+from .widget_int import IntTextWidget, BoundedIntTextWidget, IntSliderWidget, IntProgressWidget
 from .widget_selection import RadioButtonsWidget, ToggleButtonsWidget, DropdownWidget, SelectWidget
 from .widget_selectioncontainer import TabWidget, AccordionWidget
 from .widget_string import HTMLWidget, LatexWidget, TextWidget, TextareaWidget
-from .interaction import interact, interactive, fixed
diff --git a/IPython/html/widgets/interaction.py b/IPython/html/widgets/interaction.py
index 1b59de8..86c7125 100644
--- a/IPython/html/widgets/interaction.py
+++ b/IPython/html/widgets/interaction.py
@@ -21,9 +21,9 @@ except ImportError:
 from inspect import getcallargs
 
 from IPython.core.getipython import get_ipython
-from IPython.html.widgets import (Widget, TextWidget,
-    FloatSliderWidget, IntSliderWidget, CheckboxWidget, DropdownWidget,
-    ContainerWidget, DOMWidget)
+from IPython.html.widgets import (Widget, Text,
+    FloatSlider, IntSlider, Checkbox, Dropdown,
+    Box, DOMWidget)
 from IPython.display import display, clear_output
 from IPython.utils.py3compat import string_types, unicode_type
 from IPython.utils.traitlets import HasTraits, Any, Unicode
@@ -70,17 +70,17 @@ def _get_min_max_value(min, max, value=None, step=None):
 def _widget_abbrev_single_value(o):
     """Make widgets from single values, which can be used as parameter defaults."""
     if isinstance(o, string_types):
-        return TextWidget(value=unicode_type(o))
+        return Text(value=unicode_type(o))
     elif isinstance(o, dict):
-        return DropdownWidget(values=o)
+        return Dropdown(values=o)
     elif isinstance(o, bool):
-        return CheckboxWidget(value=o)
+        return Checkbox(value=o)
     elif isinstance(o, float):
         min, max, value = _get_min_max_value(None, None, o)
-        return FloatSliderWidget(value=o, min=min, max=max)
+        return FloatSlider(value=o, min=min, max=max)
     elif isinstance(o, int):
         min, max, value = _get_min_max_value(None, None, o)
-        return IntSliderWidget(value=o, min=min, max=max)
+        return IntSlider(value=o, min=min, max=max)
     else:
         return None
 
@@ -89,13 +89,13 @@ def _widget_abbrev(o):
     float_or_int = (float, int)
     if isinstance(o, (list, tuple)):
         if o and all(isinstance(x, string_types) for x in o):
-            return DropdownWidget(values=[unicode_type(k) for k in o])
+            return Dropdown(values=[unicode_type(k) for k in o])
         elif _matches(o, (float_or_int, float_or_int)):
             min, max, value = _get_min_max_value(o[0], o[1])
             if all(isinstance(_, int) for _ in o):
-                cls = IntSliderWidget
+                cls = IntSlider
             else:
-                cls = FloatSliderWidget
+                cls = FloatSlider
             return cls(value=value, min=min, max=max)
         elif _matches(o, (float_or_int, float_or_int, float_or_int)):
             step = o[2]
@@ -103,9 +103,9 @@ def _widget_abbrev(o):
                 raise ValueError("step must be >= 0, not %r" % step)
             min, max, value = _get_min_max_value(o[0], o[1], step=step)
             if all(isinstance(_, int) for _ in o):
-                cls = IntSliderWidget
+                cls = IntSlider
             else:
-                cls = FloatSliderWidget
+                cls = FloatSlider
             return cls(value=value, min=min, max=max, step=step)
     else:
         return _widget_abbrev_single_value(o)
@@ -176,7 +176,7 @@ def interactive(__interact_f, **kwargs):
     f = __interact_f
     co = kwargs.pop('clear_output', True)
     kwargs_widgets = []
-    container = ContainerWidget()
+    container = Box()
     container.result = None
     container.args = []
     container.kwargs = dict()
diff --git a/IPython/html/widgets/tests/test_interaction.py b/IPython/html/widgets/tests/test_interaction.py
index df15577..74d00c4 100644
--- a/IPython/html/widgets/tests/test_interaction.py
+++ b/IPython/html/widgets/tests/test_interaction.py
@@ -92,7 +92,7 @@ def test_single_value_string():
     c = interactive(f, a=a)
     w = c.children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         description='a',
         value=a,
     )
@@ -102,7 +102,7 @@ def test_single_value_bool():
         c = interactive(f, a=a)
         w = c.children[0]
         check_widget(w,
-            cls=widgets.CheckboxWidget,
+            cls=widgets.Checkbox,
             description='a',
             value=a,
         )
@@ -115,7 +115,7 @@ def test_single_value_dict():
         c = interactive(f, d=d)
         w = c.children[0]
         check_widget(w,
-            cls=widgets.DropdownWidget,
+            cls=widgets.Dropdown,
             description='d',
             values=d,
             value=next(iter(d.values())),
@@ -126,7 +126,7 @@ def test_single_value_float():
         c = interactive(f, a=a)
         w = c.children[0]
         check_widget(w,
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             description='a',
             value=a,
             min= -a if a > 0 else 3*a,
@@ -141,7 +141,7 @@ def test_single_value_int():
         nt.assert_equal(len(c.children), 1)
         w = c.children[0]
         check_widget(w,
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             description='a',
             value=a,
             min= -a if a > 0 else 3*a,
@@ -159,7 +159,7 @@ def test_list_tuple_2_int():
         c = interactive(f, tup=(min, max), lis=[min, max])
         nt.assert_equal(len(c.children), 2)
         d = dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             min=min,
             max=max,
             step=1,
@@ -176,7 +176,7 @@ def test_list_tuple_3_int():
         c = interactive(f, tup=(min, max, step), lis=[min, max, step])
         nt.assert_equal(len(c.children), 2)
         d = dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             min=min,
             max=max,
             step=step,
@@ -193,7 +193,7 @@ def test_list_tuple_2_float():
         c = interactive(f, tup=(min, max), lis=[min, max])
         nt.assert_equal(len(c.children), 2)
         d = dict(
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             min=min,
             max=max,
             step=.1,
@@ -212,7 +212,7 @@ def test_list_tuple_3_float():
         c = interactive(f, tup=(min, max, step), lis=[min, max, step])
         nt.assert_equal(len(c.children), 2)
         d = dict(
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             min=min,
             max=max,
             step=step,
@@ -227,7 +227,7 @@ def test_list_tuple_str():
     c = interactive(f, tup=tuple(values), lis=list(values))
     nt.assert_equal(len(c.children), 2)
     d = dict(
-        cls=widgets.DropdownWidget,
+        cls=widgets.Dropdown,
         value=first,
         values=dvalues
     )
@@ -253,15 +253,15 @@ def test_defaults():
     c = interactive(f)
     check_widgets(c,
         n=dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             value=10,
         ),
         f=dict(
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             value=4.5,
         ),
         g=dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             value=1,
         ),
     )
@@ -274,24 +274,24 @@ def test_default_values():
     c = interactive(f)
     check_widgets(c,
         n=dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             value=10,
         ),
         f=dict(
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             value=4.5,
         ),
         g=dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             value=5,
         ),
         h=dict(
-            cls=widgets.DropdownWidget,
+            cls=widgets.Dropdown,
             values={'a': 1, 'b': 2},
             value=2
         ),
         j=dict(
-            cls=widgets.DropdownWidget,
+            cls=widgets.Dropdown,
             values={'hi':'hi', 'there':'there'},
             value='there'
         ),
@@ -305,34 +305,34 @@ def test_default_out_of_bounds():
     c = interactive(f)
     check_widgets(c,
         f=dict(
-            cls=widgets.FloatSliderWidget,
+            cls=widgets.FloatSlider,
             value=5.,
         ),
         h=dict(
-            cls=widgets.DropdownWidget,
+            cls=widgets.Dropdown,
             values={'a': 1},
             value=1,
         ),
         j=dict(
-            cls=widgets.DropdownWidget,
+            cls=widgets.Dropdown,
             values={'hi':'hi', 'there':'there'},
             value='hi',
         ),
     )
 
 def test_annotations():
-    @annotate(n=10, f=widgets.FloatTextWidget())
+    @annotate(n=10, f=widgets.FloatText())
     def f(n, f):
         pass
     
     c = interactive(f)
     check_widgets(c,
         n=dict(
-            cls=widgets.IntSliderWidget,
+            cls=widgets.IntSlider,
             value=10,
         ),
         f=dict(
-            cls=widgets.FloatTextWidget,
+            cls=widgets.FloatText,
         ),
     )
 
@@ -344,11 +344,11 @@ def test_priority():
     c = interactive(f, kwarg='kwarg')
     check_widgets(c,
         kwarg=dict(
-            cls=widgets.TextWidget,
+            cls=widgets.Text,
             value='kwarg',
         ),
         annotate=dict(
-            cls=widgets.TextWidget,
+            cls=widgets.Text,
             value='annotate',
         ),
     )
@@ -362,7 +362,7 @@ def test_decorator_kwarg():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.IntSliderWidget,
+        cls=widgets.IntSlider,
         value=5,
     )
 
@@ -375,7 +375,7 @@ def test_decorator_no_call():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='default',
     )
 
@@ -388,7 +388,7 @@ def test_call_interact():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='default',
     )
 
@@ -401,7 +401,7 @@ def test_call_interact_kwargs():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.IntSliderWidget,
+        cls=widgets.IntSlider,
         value=10,
     )
 
@@ -417,7 +417,7 @@ def test_call_decorated_on_trait_change():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='default',
     )
     # test calling the function directly
@@ -441,7 +441,7 @@ def test_call_decorated_kwargs_on_trait_change():
     nt.assert_equal(len(displayed), 1)
     w = displayed[0].children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='kwarg',
     )
     # test calling the function directly
@@ -458,7 +458,7 @@ def test_fixed():
     nt.assert_equal(len(c.children), 1)
     w = c.children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='text',
         description='b',
     )
@@ -467,22 +467,22 @@ def test_default_description():
     c = interactive(f, b='text')
     w = c.children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='text',
         description='b',
     )
 
 def test_custom_description():
-    c = interactive(f, b=widgets.TextWidget(value='text', description='foo'))
+    c = interactive(f, b=widgets.Text(value='text', description='foo'))
     w = c.children[0]
     check_widget(w,
-        cls=widgets.TextWidget,
+        cls=widgets.Text,
         value='text',
         description='foo',
     )
 
 def test_int_range_logic():
-    irsw = widgets.IntRangeSliderWidget
+    irsw = widgets.IntRangeSlider
     w = irsw(value=(2, 4), min=0, max=6)
     check_widget(w, cls=irsw, value=(2, 4), min=0, max=6)
     w.value = (4, 2)
@@ -537,7 +537,7 @@ def test_int_range_logic():
     
 
 def test_float_range_logic():
-    frsw = widgets.FloatRangeSliderWidget
+    frsw = widgets.FloatRangeSlider
     w = frsw(value=(.2, .4), min=0., max=.6)
     check_widget(w, cls=frsw, value=(.2, .4), min=0., max=.6)
     w.value = (.4, .2)
@@ -588,4 +588,4 @@ def test_float_range_logic():
     with nt.assert_raises(ValueError):
         frsw(value=(2, 4), lower=3, upper=3)
     with nt.assert_raises(ValueError):
-        frsw(min=.2, max=.1)
\ No newline at end of file
+        frsw(min=.2, max=.1)
diff --git a/IPython/html/widgets/widget_bool.py b/IPython/html/widgets/widget_bool.py
index ac07d7f..b7bbb1d 100644
--- a/IPython/html/widgets/widget_bool.py
+++ b/IPython/html/widgets/widget_bool.py
@@ -1,4 +1,4 @@
-"""BoolWidget class.  
+"""Bool class.  
 
 Represents a boolean using a widget.
 """
@@ -15,20 +15,29 @@ Represents a boolean using a widget.
 #-----------------------------------------------------------------------------
 from .widget import DOMWidget
 from IPython.utils.traitlets import Unicode, Bool
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class _BoolWidget(DOMWidget):
+class _Bool(DOMWidget):
+    """A base class for creating widgets that represent booleans."""
     value = Bool(False, help="Bool value", sync=True)
-    description = Unicode('', help="Description of the boolean (label).", sync=True) 
+    description = Unicode('', help="Description of the boolean (label).", sync=True)
     disabled = Bool(False, help="Enable or disable user changes.", sync=True)
 
 
-class CheckboxWidget(_BoolWidget):
+class Checkbox(_Bool):
+    """Displays a boolean `value`."""
     _view_name = Unicode('CheckboxView', sync=True)
 
 
-class ToggleButtonWidget(_BoolWidget):
-    _view_name = Unicode('ToggleButtonView', sync=True)
+class ToggleButton(_Bool):
+    """Displays a boolean `value`."""
     
+    _view_name = Unicode('ToggleButtonView', sync=True)
+
+
+# Remove in IPython 4.0
+CheckboxWidget = DeprecatedClass(Checkbox, 'CheckboxWidget')
+ToggleButtonWidget = DeprecatedClass(ToggleButton, 'ToggleButtonWidget')
diff --git a/IPython/html/widgets/widget_box.py b/IPython/html/widgets/widget_box.py
new file mode 100644
index 0000000..bd204bd
--- /dev/null
+++ b/IPython/html/widgets/widget_box.py
@@ -0,0 +1,73 @@
+"""Box class.  
+
+Represents a container that can be used to group other widgets.
+"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from .widget import DOMWidget
+from IPython.utils.traitlets import Unicode, Tuple, TraitError, Int, CaselessStrEnum
+from IPython.utils.warn import DeprecatedClass
+
+class Box(DOMWidget):
+    """Displays multiple widgets in a group."""
+    _view_name = Unicode('BoxView', sync=True)
+
+    # Child widgets in the container.
+    # Using a tuple here to force reassignment to update the list.
+    # When a proper notifying-list trait exists, that is what should be used here.
+    children = Tuple(sync=True, allow_none=False)
+
+    def __init__(self, children = (), **kwargs):
+        kwargs['children'] = children
+        super(Box, self).__init__(**kwargs)
+        self.on_displayed(Box._fire_children_displayed)
+
+    def _fire_children_displayed(self):
+        for child in self.children:
+            child._handle_displayed()
+
+
+class Popup(Box):
+    """Displays multiple widgets in an in page popup div."""
+    _view_name = Unicode('PopupView', sync=True)
+    
+    description = Unicode(sync=True)
+    button_text = Unicode(sync=True)
+
+
+class FlexBox(Box):
+    """Displays multiple widgets using the flexible box model."""
+    _view_name = Unicode('FlexBoxView', sync=True)
+    orientation = CaselessStrEnum(values=['vertical', 'horizontal'], default_value='vertical', sync=True)
+    flex = Int(0, sync=True, help="""Specify the flexible-ness of the model.""")
+    def _flex_changed(self, name, old, new):
+        new = min(max(0, new), 2)
+        if self.flex != new:
+            self.flex = new
+
+    _locations = ['start', 'center', 'end', 'baseline', 'stretch']
+    pack = CaselessStrEnum(
+        values=_locations, 
+        default_value='start', allow_none=False, sync=True)
+    align = CaselessStrEnum(
+        values=_locations, 
+        default_value='start', allow_none=False, sync=True)
+
+
+def VBox(*pargs, **kwargs):
+    """Displays multiple widgets vertically using the flexible box model."""
+    kwargs['orientation'] = 'vertical'
+    return FlexBox(*pargs, **kwargs)
+
+def HBox(*pargs, **kwargs):
+    """Displays multiple widgets horizontally using the flexible box model."""
+    kwargs['orientation'] = 'horizontal'
+    return FlexBox(*pargs, **kwargs)
+
+
+# Remove in IPython 4.0
+ContainerWidget = DeprecatedClass(Box, 'ContainerWidget')
+PopupWidget = DeprecatedClass(Popup, 'PopupWidget')
+
diff --git a/IPython/html/widgets/widget_button.py b/IPython/html/widgets/widget_button.py
index 3fdfe72..17774cc 100644
--- a/IPython/html/widgets/widget_button.py
+++ b/IPython/html/widgets/widget_button.py
@@ -1,4 +1,4 @@
-"""ButtonWidget class.  
+"""Button class.  
 
 Represents a button in the frontend using a widget.  Allows user to listen for
 click events on the button and trigger backend code when the clicks are fired.
@@ -16,11 +16,16 @@ click events on the button and trigger backend code when the clicks are fired.
 #-----------------------------------------------------------------------------
 from .widget import DOMWidget, CallbackDispatcher
 from IPython.utils.traitlets import Unicode, Bool
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class ButtonWidget(DOMWidget):
+class Button(DOMWidget):
+    """Button widget.
+
+    This widget has an `on_click` method that allows you to listen for the 
+    user clicking on the button.  The click event itself is stateless."""
     _view_name = Unicode('ButtonView', sync=True)
 
     # Keys
@@ -29,7 +34,7 @@ class ButtonWidget(DOMWidget):
     
     def __init__(self, **kwargs):
         """Constructor"""
-        super(ButtonWidget, self).__init__(**kwargs)
+        super(Button, self).__init__(**kwargs)
         self._click_handlers = CallbackDispatcher()
         self.on_msg(self._handle_button_msg)
 
@@ -54,3 +59,7 @@ class ButtonWidget(DOMWidget):
             Content of the msg."""
         if content.get('event', '') == 'click':
             self._click_handlers(self)
+
+
+# Remove in IPython 4.0
+ButtonWidget = DeprecatedClass(Button, 'ButtonWidget')
diff --git a/IPython/html/widgets/widget_container.py b/IPython/html/widgets/widget_container.py
deleted file mode 100644
index 6ba8206..0000000
--- a/IPython/html/widgets/widget_container.py
+++ /dev/null
@@ -1,34 +0,0 @@
-"""ContainerWidget class.  
-
-Represents a container that can be used to group other widgets.
-"""
-
-# Copyright (c) IPython Development Team.
-# Distributed under the terms of the Modified BSD License.
-
-from .widget import DOMWidget
-from IPython.utils.traitlets import Unicode, Tuple, TraitError
-
-class ContainerWidget(DOMWidget):
-    _view_name = Unicode('ContainerView', sync=True)
-
-    # Child widgets in the container.
-    # Using a tuple here to force reassignment to update the list.
-    # When a proper notifying-list trait exists, that is what should be used here.
-    children = Tuple(sync=True, allow_none=False)
-
-    def __init__(self, children = (), **kwargs):
-        kwargs['children'] = children
-        super(ContainerWidget, self).__init__(**kwargs)
-        self.on_displayed(ContainerWidget._fire_children_displayed)
-
-    def _fire_children_displayed(self):
-        for child in self.children:
-            child._handle_displayed()
-
-
-class PopupWidget(ContainerWidget):
-    _view_name = Unicode('PopupView', sync=True)
-    
-    description = Unicode(sync=True)
-    button_text = Unicode(sync=True)
diff --git a/IPython/html/widgets/widget_float.py b/IPython/html/widgets/widget_float.py
index db7b350..e5d5aac 100644
--- a/IPython/html/widgets/widget_float.py
+++ b/IPython/html/widgets/widget_float.py
@@ -1,4 +1,4 @@
-"""FloatWidget class.
+"""Float class.  
 
 Represents an unbounded float using a widget.
 """
@@ -15,17 +15,18 @@ Represents an unbounded float using a widget.
 #-----------------------------------------------------------------------------
 from .widget import DOMWidget
 from IPython.utils.traitlets import Unicode, CFloat, Bool, Enum, Tuple
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class _FloatWidget(DOMWidget):
-    value = CFloat(0.0, help="Float value", sync=True)
+class _Float(DOMWidget):
+    value = CFloat(0.0, help="Float value", sync=True) 
     disabled = Bool(False, help="Enable or disable user changes", sync=True)
     description = Unicode(help="Description of the value this widget represents", sync=True)
 
 
-class _BoundedFloatWidget(_FloatWidget):
+class _BoundedFloat(_Float):
     max = CFloat(100.0, help="Max value", sync=True)
     min = CFloat(0.0, help="Min value", sync=True)
     step = CFloat(0.1, help="Minimum step that the value can take (ignored by some views)", sync=True)
@@ -42,26 +43,26 @@ class _BoundedFloatWidget(_FloatWidget):
             self.value = min(max(new, self.min), self.max)
 
 
-class FloatTextWidget(_FloatWidget):
+class FloatText(_Float):
     _view_name = Unicode('FloatTextView', sync=True)
 
 
-class BoundedFloatTextWidget(_BoundedFloatWidget):
+class BoundedFloatText(_BoundedFloat):
     _view_name = Unicode('FloatTextView', sync=True)
 
 
-class FloatSliderWidget(_BoundedFloatWidget):
+class FloatSlider(_BoundedFloat):
     _view_name = Unicode('FloatSliderView', sync=True)
-    orientation = Enum([u'horizontal', u'vertical'], u'horizontal',
+    orientation = Enum([u'horizontal', u'vertical'], u'horizontal', 
         help="Vertical or horizontal.", sync=True)
     range = Bool(False, help="Display a range selector", sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.", sync=True)
 
 
-class FloatProgressWidget(_BoundedFloatWidget):
+class FloatProgress(_BoundedFloat):
     _view_name = Unicode('ProgressView', sync=True)
 
-class _FloatRangeWidget(_FloatWidget):
+class _FloatRange(_Float):
     value = Tuple(CFloat, CFloat, default_value=(0.0, 1.0), help="Tuple of (lower, upper) bounds", sync=True)
     lower = CFloat(0.0, help="Lower bound", sync=False)
     upper = CFloat(1.0, help="Upper bound", sync=False)
@@ -90,14 +91,14 @@ class _FloatRangeWidget(_FloatWidget):
         elif name == 'upper':
             self.value = (self.value[0], new)
 
-class _BoundedFloatRangeWidget(_FloatRangeWidget):
+class _BoundedFloatRange(_FloatRange):
     step = CFloat(1.0, help="Minimum step that the value can take (ignored by some views)", sync=True)
     max = CFloat(100.0, help="Max value", sync=True)
     min = CFloat(0.0, help="Min value", sync=True)
     
     def __init__(self, *pargs, **kwargs):
         any_value_given = 'value' in kwargs or 'upper' in kwargs or 'lower' in kwargs
-        _FloatRangeWidget.__init__(self, *pargs, **kwargs)
+        _FloatRange.__init__(self, *pargs, **kwargs)
         
         # ensure a minimal amount of sanity
         if self.min > self.max:
@@ -156,9 +157,15 @@ class _BoundedFloatRangeWidget(_FloatRangeWidget):
             self.lower = low
 
 
-class FloatRangeSliderWidget(_BoundedFloatRangeWidget):
+class FloatRangeSlider(_BoundedFloatRange):
     _view_name = Unicode('FloatSliderView', sync=True)
     orientation = Enum([u'horizontal', u'vertical'], u'horizontal',
         help="Vertical or horizontal.", sync=True)
     range = Bool(True, help="Display a range selector", sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.", sync=True)
+
+# Remove in IPython 4.0
+FloatTextWidget = DeprecatedClass(FloatText, 'FloatTextWidget')
+BoundedFloatTextWidget = DeprecatedClass(BoundedFloatText, 'BoundedFloatTextWidget')
+FloatSliderWidget = DeprecatedClass(FloatSlider, 'FloatSliderWidget')
+FloatProgressWidget = DeprecatedClass(FloatProgress, 'FloatProgressWidget')
diff --git a/IPython/html/widgets/widget_image.py b/IPython/html/widgets/widget_image.py
index 0e18bde..f8ff8d4 100644
--- a/IPython/html/widgets/widget_image.py
+++ b/IPython/html/widgets/widget_image.py
@@ -1,4 +1,4 @@
-"""ImageWidget class.  
+"""Image class.  
 
 Represents an image in the frontend using a widget.
 """
@@ -17,11 +17,18 @@ import base64
 
 from .widget import DOMWidget
 from IPython.utils.traitlets import Unicode, CUnicode, Bytes
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class ImageWidget(DOMWidget):
+class Image(DOMWidget):
+    """Displays an image as a widget.
+
+    The `value` of this widget accepts a byte string.  The byte string is the raw
+    image data that you want the browser to display.  You can explicitly define
+    the format of the byte string using the `format` trait (which defaults to
+    "png")."""
     _view_name = Unicode('ImageView', sync=True)
     
     # Define the custom state properties to sync with the front-end
@@ -33,3 +40,7 @@ class ImageWidget(DOMWidget):
     value = Bytes()
     def _value_changed(self, name, old, new):
         self._b64value = base64.b64encode(new)
+
+
+# Remove in IPython 4.0
+ImageWidget = DeprecatedClass(Image, 'ImageWidget')
diff --git a/IPython/html/widgets/widget_int.py b/IPython/html/widgets/widget_int.py
index f2f4f92..4497990 100644
--- a/IPython/html/widgets/widget_int.py
+++ b/IPython/html/widgets/widget_int.py
@@ -1,4 +1,4 @@
-"""IntWidget class.
+"""Int class.  
 
 Represents an unbounded int using a widget.
 """
@@ -15,17 +15,21 @@ Represents an unbounded int using a widget.
 #-----------------------------------------------------------------------------
 from .widget import DOMWidget
 from IPython.utils.traitlets import Unicode, CInt, Bool, Enum, Tuple
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class _IntWidget(DOMWidget):
-    value = CInt(0, help="Int value", sync=True)
+class _Int(DOMWidget):
+    """Base class used to create widgets that represent an int."""
+    value = CInt(0, help="Int value", sync=True) 
     disabled = Bool(False, help="Enable or disable user changes", sync=True)
     description = Unicode(help="Description of the value this widget represents", sync=True)
 
 
-class _BoundedIntWidget(_IntWidget):
+class _BoundedInt(_Int):
+    """Base class used to create widgets that represent a int that is bounded
+    by a minium and maximum."""
     step = CInt(1, help="Minimum step that the value can take (ignored by some views)", sync=True)
     max = CInt(100, help="Max value", sync=True)
     min = CInt(0, help="Min value", sync=True)
@@ -41,26 +45,30 @@ class _BoundedIntWidget(_IntWidget):
             self.value = min(max(new, self.min), self.max)
 
 
-class IntTextWidget(_IntWidget):
+class IntText(_Int):
+    """Textbox widget that represents a int."""
     _view_name = Unicode('IntTextView', sync=True)
 
 
-class BoundedIntTextWidget(_BoundedIntWidget):
+class BoundedIntText(_BoundedInt):
+    """Textbox widget that represents a int bounded by a minimum and maximum value."""
     _view_name = Unicode('IntTextView', sync=True)
 
 
-class IntSliderWidget(_BoundedIntWidget):
+class IntSlider(_BoundedInt):
+    """Slider widget that represents a int bounded by a minimum and maximum value."""
     _view_name = Unicode('IntSliderView', sync=True)
-    orientation = Enum([u'horizontal', u'vertical'], u'horizontal',
+    orientation = Enum([u'horizontal', u'vertical'], u'horizontal', 
         help="Vertical or horizontal.", sync=True)
     range = Bool(False, help="Display a range selector", sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.", sync=True)
 
 
-class IntProgressWidget(_BoundedIntWidget):
+class IntProgress(_BoundedInt):
+    """Progress bar that represents a int bounded by a minimum and maximum value."""
     _view_name = Unicode('ProgressView', sync=True)
 
-class _IntRangeWidget(_IntWidget):
+class _IntRange(_Int):
     value = Tuple(CInt, CInt, default_value=(0, 1), help="Tuple of (lower, upper) bounds", sync=True)
     lower = CInt(0, help="Lower bound", sync=False)
     upper = CInt(1, help="Upper bound", sync=False)
@@ -89,14 +97,14 @@ class _IntRangeWidget(_IntWidget):
         elif name == 'upper':
             self.value = (self.value[0], new)
 
-class _BoundedIntRangeWidget(_IntRangeWidget):
+class _BoundedIntRange(_IntRange):
     step = CInt(1, help="Minimum step that the value can take (ignored by some views)", sync=True)
     max = CInt(100, help="Max value", sync=True)
     min = CInt(0, help="Min value", sync=True)
 
     def __init__(self, *pargs, **kwargs):
         any_value_given = 'value' in kwargs or 'upper' in kwargs or 'lower' in kwargs
-        _IntRangeWidget.__init__(self, *pargs, **kwargs)
+        _IntRange.__init__(self, *pargs, **kwargs)
         
         # ensure a minimal amount of sanity
         if self.min > self.max:
@@ -153,9 +161,15 @@ class _BoundedIntRangeWidget(_IntRangeWidget):
             self.upper = high
             self.lower = low
 
-class IntRangeSliderWidget(_BoundedIntRangeWidget):
+class IntRangeSlider(_BoundedIntRange):
     _view_name = Unicode('IntSliderView', sync=True)
     orientation = Enum([u'horizontal', u'vertical'], u'horizontal',
         help="Vertical or horizontal.", sync=True)
     range = Bool(True, help="Display a range selector", sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.", sync=True)
+
+# Remove in IPython 4.0
+IntTextWidget = DeprecatedClass(IntText, 'IntTextWidget')
+BoundedIntTextWidget = DeprecatedClass(BoundedIntText, 'BoundedIntTextWidget')
+IntSliderWidget = DeprecatedClass(IntSlider, 'IntSliderWidget')
+IntProgressWidget = DeprecatedClass(IntProgress, 'IntProgressWidget')
diff --git a/IPython/html/widgets/widget_selection.py b/IPython/html/widgets/widget_selection.py
index e9706d1..7c4f2f1 100644
--- a/IPython/html/widgets/widget_selection.py
+++ b/IPython/html/widgets/widget_selection.py
@@ -1,4 +1,4 @@
-"""SelectionWidget classes.
+"""Selection classes.
 
 Represents an enumeration using a widget.
 """
@@ -20,11 +20,12 @@ from threading import Lock
 from .widget import DOMWidget
 from IPython.utils.traitlets import Unicode, List, Bool, Any, Dict, TraitError
 from IPython.utils.py3compat import unicode_type
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # SelectionWidget
 #-----------------------------------------------------------------------------
-class _SelectionWidget(DOMWidget):
+class _Selection(DOMWidget):
     """Base class for Selection widgets
     
     ``values`` can be specified as a list or dict. If given as a list,
@@ -109,17 +110,30 @@ class _SelectionWidget(DOMWidget):
                 self.value_lock.release()
 
 
-class ToggleButtonsWidget(_SelectionWidget):
+class ToggleButtons(_Selection):
+    """Group of toggle buttons that represent an enumeration.  Only one toggle
+    button can be toggled at any point in time.""" 
     _view_name = Unicode('ToggleButtonsView', sync=True)
 
 
-class DropdownWidget(_SelectionWidget):
+class Dropdown(_Selection):
+    """Allows you to select a single item from a dropdown."""
     _view_name = Unicode('DropdownView', sync=True)
 
 
-class RadioButtonsWidget(_SelectionWidget):
+class RadioButtons(_Selection):
+    """Group of radio buttons that represent an enumeration.  Only one radio
+    button can be toggled at any point in time.""" 
     _view_name = Unicode('RadioButtonsView', sync=True)
     
 
-class SelectWidget(_SelectionWidget):
+class Select(_Selection):
+    """Listbox that only allows one item to be selected at any given time."""
     _view_name = Unicode('SelectView', sync=True)
+
+
+# Remove in IPython 4.0
+ToggleButtonsWidget = DeprecatedClass(ToggleButtons, 'ToggleButtonsWidget')
+DropdownWidget = DeprecatedClass(Dropdown, 'DropdownWidget')
+RadioButtonsWidget = DeprecatedClass(RadioButtons, 'RadioButtonsWidget')
+SelectWidget = DeprecatedClass(Select, 'SelectWidget')
diff --git a/IPython/html/widgets/widget_selectioncontainer.py b/IPython/html/widgets/widget_selectioncontainer.py
index ef91559..729090b 100644
--- a/IPython/html/widgets/widget_selectioncontainer.py
+++ b/IPython/html/widgets/widget_selectioncontainer.py
@@ -1,4 +1,4 @@
-"""SelectionContainerWidget class.  
+"""SelectionContainer class.  
 
 Represents a multipage container that can be used to group other widgets into
 pages.
@@ -14,13 +14,15 @@ pages.
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
-from .widget_container import ContainerWidget
+from .widget_box import Box
 from IPython.utils.traitlets import Unicode, Dict, CInt
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class _SelectionContainerWidget(ContainerWidget):
+class _SelectionContainer(Box):
+    """Base class used to display multiple child widgets."""
     _titles = Dict(help="Titles of the pages", sync=True)
     selected_index = CInt(0, sync=True)
 
@@ -50,9 +52,16 @@ class _SelectionContainerWidget(ContainerWidget):
             return None
 
 
-class AccordionWidget(_SelectionContainerWidget):
+class Accordion(_SelectionContainer):
+    """Displays children each on a separate accordion page."""
     _view_name = Unicode('AccordionView', sync=True)
 
 
-class TabWidget(_SelectionContainerWidget):
+class Tab(_SelectionContainer):
+    """Displays children each on a separate accordion tab."""
     _view_name = Unicode('TabView', sync=True)
+
+
+# Remove in IPython 4.0
+AccordionWidget = DeprecatedClass(Accordion, 'AccordionWidget')
+TabWidget = DeprecatedClass(Tab, 'TabWidget')
diff --git a/IPython/html/widgets/widget_string.py b/IPython/html/widgets/widget_string.py
index 9f6aa30..26b06cc 100644
--- a/IPython/html/widgets/widget_string.py
+++ b/IPython/html/widgets/widget_string.py
@@ -1,4 +1,4 @@
-"""StringWidget class.  
+"""String class.  
 
 Represents a unicode string using a widget.
 """
@@ -15,37 +15,44 @@ Represents a unicode string using a widget.
 #-----------------------------------------------------------------------------
 from .widget import DOMWidget, CallbackDispatcher
 from IPython.utils.traitlets import Unicode, Bool
+from IPython.utils.warn import DeprecatedClass
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class _StringWidget(DOMWidget):
+class _String(DOMWidget):
+    """Base class used to create widgets that represent a string."""
     value = Unicode(help="String value", sync=True)
     disabled = Bool(False, help="Enable or disable user changes", sync=True)
     description = Unicode(help="Description of the value this widget represents", sync=True)
     placeholder = Unicode("", help="Placeholder text to display when nothing has been typed", sync=True)
 
 
-class HTMLWidget(_StringWidget):
+class HTML(_String):
+    """Renders the string `value` as HTML."""
     _view_name = Unicode('HTMLView', sync=True)
 
 
-class LatexWidget(_StringWidget):
+class Latex(_String):
+    """Renders math inside the string `value` as Latex (requires $ $ or $$ $$ 
+    and similar latex tags)."""
     _view_name = Unicode('LatexView', sync=True)
 
 
-class TextareaWidget(_StringWidget):
+class Textarea(_String):
+    """Multiline text area widget."""
     _view_name = Unicode('TextareaView', sync=True)
 
     def scroll_to_bottom(self):
         self.send({"method": "scroll_to_bottom"})
 
 
-class TextWidget(_StringWidget):
+class Text(_String):
+    """Single line textbox widget."""
     _view_name = Unicode('TextView', sync=True)
 
     def __init__(self, **kwargs):
-        super(TextWidget, self).__init__(**kwargs)
+        super(Text, self).__init__(**kwargs)
         self._submission_callbacks = CallbackDispatcher()
         self.on_msg(self._handle_string_msg)
 
@@ -71,3 +78,10 @@ class TextWidget(_StringWidget):
         remove: bool (optional)
             Whether to unregister the callback"""
         self._submission_callbacks.register_callback(callback, remove=remove)
+
+
+# Remove in IPython 4.0
+HTMLWidget = DeprecatedClass(HTML, 'HTMLWidget')
+LatexWidget = DeprecatedClass(Latex, 'LatexWidget')
+TextareaWidget = DeprecatedClass(Textarea, 'TextareaWidget')
+TextWidget = DeprecatedClass(Text, 'TextWidget')
diff --git a/IPython/kernel/kernelspec.py b/IPython/kernel/kernelspec.py
index c708a8c..f129886 100644
--- a/IPython/kernel/kernelspec.py
+++ b/IPython/kernel/kernelspec.py
@@ -8,7 +8,7 @@ pjoin = os.path.join
 
 from IPython.utils.path import get_ipython_dir
 from IPython.utils.py3compat import PY3
-from IPython.utils.traitlets import HasTraits, List, Unicode, Dict
+from IPython.utils.traitlets import HasTraits, List, Unicode, Dict, Any
 
 if os.name == 'nt':
     programdata = os.environ.get('PROGRAMDATA', None)
@@ -36,18 +36,12 @@ class KernelSpec(HasTraits):
     argv = List()
     display_name = Unicode()
     language = Unicode()
-    codemirror_mode = None
+    codemirror_mode = Any() # can be unicode or dict
     env = Dict()
-    
     resource_dir = Unicode()
     
-    def __init__(self, resource_dir, argv, display_name, language,
-                 codemirror_mode=None):
-        super(KernelSpec, self).__init__(resource_dir=resource_dir, argv=argv,
-                display_name=display_name, language=language,
-                codemirror_mode=codemirror_mode)
-        if not self.codemirror_mode:
-            self.codemirror_mode = self.language
+    def _codemirror_mode_default(self):
+        return self.language
     
     @classmethod
     def from_resource_dir(cls, resource_dir):
diff --git a/IPython/utils/_process_cli.py b/IPython/utils/_process_cli.py
index eb69d3f..a7b7b90 100644
--- a/IPython/utils/_process_cli.py
+++ b/IPython/utils/_process_cli.py
@@ -61,3 +61,18 @@ def getoutput(cmd):
     myError = reg.StandardError
     error = myError.ReadToEnd()
     return output
+
+def check_pid(pid):
+    """
+    Check if a process with the given PID (pid) exists
+    """
+    try:
+        System.Diagnostics.Process.GetProcessById(pid)
+        # process with given pid is running
+        return True
+    except System.InvalidOperationException:
+        # process wasn't started by this object (but is running)
+        return True
+    except System.ArgumentException:
+        # process with given pid isn't running
+        return False 
diff --git a/IPython/utils/process.py b/IPython/utils/process.py
index 2a19945..64b7254 100644
--- a/IPython/utils/process.py
+++ b/IPython/utils/process.py
@@ -23,7 +23,7 @@ import sys
 if sys.platform == 'win32':
     from ._process_win32 import _find_cmd, system, getoutput, arg_split, check_pid
 elif sys.platform == 'cli':
-    from ._process_cli import _find_cmd, system, getoutput, arg_split
+    from ._process_cli import _find_cmd, system, getoutput, arg_split, check_pid
 else:
     from ._process_posix import _find_cmd, system, getoutput, arg_split, check_pid
 
diff --git a/IPython/utils/tests/test_traitlets.py b/IPython/utils/tests/test_traitlets.py
index fcb3ca2..9251ae8 100644
--- a/IPython/utils/tests/test_traitlets.py
+++ b/IPython/utils/tests/test_traitlets.py
@@ -406,6 +406,13 @@ class TestHasTraits(TestCase):
         a = A()
         self.assertEqual(a.trait_metadata('i','config_key'), 'MY_VALUE')
 
+    def test_trait_metadata_default(self):
+        class A(HasTraits):
+            i = Int()
+        a = A()
+        self.assertEqual(a.trait_metadata('i', 'config_key'), None)
+        self.assertEqual(a.trait_metadata('i', 'config_key', 'default'), 'default')
+
     def test_traits(self):
         class A(HasTraits):
             i = Int
diff --git a/IPython/utils/traitlets.py b/IPython/utils/traitlets.py
index 7b65196..c81f68a 100644
--- a/IPython/utils/traitlets.py
+++ b/IPython/utils/traitlets.py
@@ -458,8 +458,8 @@ class TraitType(object):
                 % (self.name, self.info(), repr_type(value))
         raise TraitError(e)
 
-    def get_metadata(self, key):
-        return getattr(self, '_metadata', {}).get(key, None)
+    def get_metadata(self, key, default=None):
+        return getattr(self, '_metadata', {}).get(key, default)
 
     def set_metadata(self, key, value):
         getattr(self, '_metadata', {})[key] = value
@@ -728,7 +728,7 @@ class HasTraits(py3compat.with_metaclass(MetaHasTraits, object)):
 
         return result
 
-    def trait_metadata(self, traitname, key):
+    def trait_metadata(self, traitname, key, default=None):
         """Get metadata values for trait by key."""
         try:
             trait = getattr(self.__class__, traitname)
@@ -736,7 +736,7 @@ class HasTraits(py3compat.with_metaclass(MetaHasTraits, object)):
             raise TraitError("Class %s does not have a trait named %s" %
                                 (self.__class__.__name__, traitname))
         else:
-            return trait.get_metadata(key)
+            return trait.get_metadata(key, default)
 
 #-----------------------------------------------------------------------------
 # Actual TraitTypes implementations/subclasses
diff --git a/IPython/utils/warn.py b/IPython/utils/warn.py
index 693eeb3..6ad6acc 100644
--- a/IPython/utils/warn.py
+++ b/IPython/utils/warn.py
@@ -16,6 +16,7 @@ Utilities for warnings.  Shoudn't we just use the built in warnings module.
 from __future__ import print_function
 
 import sys
+import warnings
 
 from IPython.utils import io
 
@@ -65,3 +66,16 @@ def fatal(msg,exit_val=1):
 
     warn(msg,exit_val=exit_val,level=4)
 
+
+def DeprecatedClass(base, class_name):
+    # Hook the init method of the base class.
+    def init_hook(self, *pargs, **kwargs):
+        base.__init__(self, *pargs, **kwargs)
+
+        # Warn once per class.
+        if base not in DeprecatedClass._warned_classes:
+            DeprecatedClass._warned_classes.append(base)
+            warn('"{}" is deprecated, please use "{}" instead.'.format(
+                class_name, base.__name__))
+    return type(class_name, (base,), {'__init__': init_hook})
+DeprecatedClass._warned_classes = []
diff --git a/docs/source/whatsnew/pr/incompat-deprecated-widget-names.rst b/docs/source/whatsnew/pr/incompat-deprecated-widget-names.rst
new file mode 100644
index 0000000..6ccd7aa
--- /dev/null
+++ b/docs/source/whatsnew/pr/incompat-deprecated-widget-names.rst
@@ -0,0 +1,6 @@
+* The widget classes have been renamed from `*Widget` to `*`.  The old names are 
+  still functional, but are deprecated.  i.e. `IntSliderWidget` has been renamed 
+  to `IntSlider`.
+* The ContainerWidget was renamed to Box and no longer defaults as a flexible
+  box in the web browser.  A new FlexBox widget was added, which allows you to
+  use the flexible box model.
diff --git a/tox.ini b/tox.ini
index 5852233..dae0b87 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,23 +3,44 @@
 # test suite on all supported python versions. To use it, "pip install tox"
 # and then run "tox" from this directory.
 
+# Building the source distribution requires both fabric's fab binary
+# (http://www.fabfile.org/) and the lessc binary of the css preprocessor
+# less (http://lesscss.org/) in the PATH.
+# "pip install fabric" will install fabric. Less can be installed by
+# node.js' (http://nodejs.org/) package manager npm:
+# "npm install -g less".
+
+# Javascript tests need additional dependencies that can be installed
+# using node.js' package manager npm:
+# [*] casperjs:  "npm install -g casperjs"
+# [*] slimerjs:  "npm install -g slimerjs"
+# [*] phantomjs: "npm install -g phantomjs"
+
+# Note: qt4 versions break some tests with tornado versions >=4.0.
+
 [tox]
-envlist = py27, py33
+envlist = py27, py33, py34
 
 [testenv]
-deps = 
+deps =
+  pyzmq
   nose
-  mock
-  tornado
+  tornado<4.0
   jinja2
   sphinx
   pygments
+  jsonpointer
+  jsonschema
+  mistune
+
 # To avoid loading IPython module in the current directory, change
 # current directory to ".tox/py*/tmp" before running test.
 changedir = {envtmpdir}
 
 commands =
-    # As pip does not treat egg, use easy_install to install PyZMQ.
-    # See also: https://github.com/zeromq/pyzmq
-    easy_install -q pyzmq
-    iptest --all
+  iptest --all
+
+[testenv:py27]
+deps=
+  mock
+  {[testenv]deps}