Made scroll to bottom use msgs

allow multiple msg handlers
added send to view to automatically hookup callbacks
changed send signature to optionally accept a cell to connect callbacks

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

@@ -36,6 +36,7 b' define(["components/underscore/underscore-min",'
             this.msg_throttle = 3;
             this.msg_buffer = null;
             this.views = {};
+            this._custom_msg_callbacks = [];
 
             // Remember comm associated with the model.
             this.comm = comm;
@@ -64,16 +65,18 b' define(["components/underscore/underscore-min",'
             }
         },
     
-        send: function(content) {
+
+        send: function(content, cell) {
 
             // Used the last modified view as the sender of the message.  This
             // will insure that any python code triggered by the sent message
             // can create and display widgets and output.
-            var cell = null;
+            if (cell === undefined) {
             if (this.last_modified_view != undefined && 
                 this.last_modified_view.cell != undefined) {
                 cell = this.last_modified_view.cell;
             }
+            }
             var callbacks = this._make_callbacks(cell);
             var data = {'custom_content': content};
             this.comm.send(data, callbacks);   
@@ -90,15 +93,29 b' define(["components/underscore/underscore-min",'
         },
 
 
-        on_msg: function (callback) {
-            this._msg_callback = callback;
+        on_msg: function (callback, remove) {
+            if (remove) {
+                var found_index = -1;
+                for (var index in this._custom_msg_callbacks) {
+                    if (callback === this._custom_msg_callbacks[index]) {
+                        found_index = index;
+                        break;
+                    }
+                }
+
+                if (found_index >= 0) {
+                    this._custom_msg_callbacks.splice(found_index, 1);
+                }
+            } else {
+                this._custom_msg_callbacks.push(callback)    
+            }
         },
 
 
         _handle_custom_msg: function (content) {
-            if (this._msg_callback) {
+            for (var index in this._custom_msg_callbacks) {
                 try {
-                    this._msg_callback(content);
+                    this._custom_msg_callbacks[index](content);
                 } catch (e) {
                     console.log("Exception in widget model msg callback", e, content);
                 }
@@ -466,6 +483,11 b' define(["components/underscore/underscore-min",'
             }
         },
 
+    
+        send: function(content) {
+            this.model.send({event: 'click'}, this.cell);
+        },
+
         update: function() {
             if (this.model.get('visible') != undefined) {
                 if (this.visible != this.model.get('visible')) {

IPython/html/static/notebook/js/widgets/button.js

@@ -50,8 +50,7 b' define(["notebook/js/widget"], function(widget_manager){'
         },
         
         _handle_click: function(){
-            this.model.last_modified_view = this; // For callbacks.
-            this.model.send({event: 'click'});
+            this.send({event: 'click'});
         },
     });
 

IPython/html/static/notebook/js/widgets/string.js

@@ -53,8 +53,23 b' define(["notebook/js/widget"], function(widget_manager){'
                 .appendTo(this.$el);
             this.$el_to_style = this.$textbox; // Set default element to style
             this.update(); // Set defaults.
+
+            this.on_msg();
+        },
+
+
+        _handle_textarea_msg: function (content){
+            if (content.method == "scroll_to_bottom") {
+                this.scroll_to_bottom();                
+            }
+        },
+
+
+        scroll_to_bottom: function (){
+            this.$textbox.scrollTop(this.$textbox[0].scrollHeight);
         },
         
+        
         // Handles: Backend -> Frontend Sync
         //          Frontent -> Frontend Sync
         update : function(){
@@ -62,14 +77,6 b' define(["notebook/js/widget"], function(widget_manager){'
                 this.$textbox.val(this.model.get('value'));
             }
 
-            if (this.last_scroll_to_bottom == undefined) {
-                this.last_scroll_to_bottom = 0;
-            }
-            if (this.last_scroll_to_bottom < this.model.get('scroll_to_bottoms')) {
-                this.last_scroll_to_bottom < this.model.get('scroll_to_bottoms');
-                this.$textbox.scrollTop(this.$textbox[0].scrollHeight);
-            }
-
             var disabled = this.model.get('disabled');
             this.$textbox.prop('disabled', disabled);
 
@@ -151,8 +158,7 b' define(["notebook/js/widget"], function(widget_manager){'
         // Handles text submition
         handleKeypress: function(e) { 
             if (e.keyCode == 13) { // Return key
-                this.model.last_modified_view = this; // For callbacks.
-                this.model.send({event: 'submit'});
+                this.send({event: 'submit'});
             }
         },
     });

IPython/html/widgets/widget_string.py

@@ -27,11 +27,10 b' class StringWidget(Widget):'
     default_view_name = Unicode('TextBoxView')
 
     # Keys
-    _keys = ['value', 'disabled', 'description', 'scroll_to_bottoms']
+    _keys = ['value', 'disabled', 'description']
     value = Unicode(help="String value")
     disabled = Bool(False, help="Enable or disable user changes")
     description = Unicode(help="Description of the value this widget represents")
-    scroll_to_bottoms = Int(0, help="Used to scroll a TextAreaView to the bottom")
 
 
     def __init__(self, **kwargs):
@@ -41,7 +40,7 b' class StringWidget(Widget):'
 
 
     def scroll_to_bottom(self):
-        self.scroll_to_bottoms += 1
+        self._comm.send({"method": "scroll_to_bottom"})
 
 
     def on_click(self, callback, remove=False):