//----------------------------------------------------------------------------
//  Copyright (C) 2013 The IPython Development Team
//
//  Distributed under the terms of the BSD License.  The full license is in
//  the file COPYING, distributed as part of this software.
//----------------------------------------------------------------------------

//============================================================================
// ButtonWidget
//============================================================================

/**
 * @module IPython
 * @namespace IPython
 **/

define(["notebook/js/widget"], function(widget_manager){
    
    var ButtonWidgetModel = IPython.WidgetModel.extend({});
    widget_manager.register_widget_model('ButtonWidgetModel', ButtonWidgetModel);

    var ButtonView = IPython.WidgetView.extend({
      
        // Called when view is rendered.
        render : function(){
            var that = this;
            this.$el = $("<button />")
                .addClass('btn')
                .click(function() {
                    that.model.set('clicks', that.model.get('clicks') + 1);
                    that.model.update_other_views(that);
                });
            this._ensureElement();

            this.update(); // Set defaults.
        },
        
        // Handles: Backend -> Frontend Sync
        //          Frontent -> Frontend Sync
        update : function(){
            var description = this.model.get('description');
            description = description.replace(/ /g, '&nbsp;', 'm');
            description = description.replace(/\n/g, '<br>\n', 'm');
            if (description.length == 0) {
                this.$el.html('&nbsp;'); // Preserve button height
            } else {
                this.$el.html(description);
            }
            
            return IPython.WidgetView.prototype.update.call(this);
        },
        
    });

    widget_manager.register_widget_view('ButtonView', ButtonView);

});

//----------------------------------------------------------------------------
//  Copyright (C) 2013 The IPython Development Team
//
//  Distributed under the terms of the BSD License.  The full license is in
//  the file COPYING, distributed as part of this software.
//----------------------------------------------------------------------------

//============================================================================
// ButtonWidget
//============================================================================

/**
 * @module IPython
 * @namespace IPython
 **/

define(["notebook/js/widget"], function(widget_manager){
    
    var ButtonWidgetModel = IPython.WidgetModel.extend({});
    widget_manager.register_widget_model('ButtonWidgetModel', ButtonWidgetModel);

    var ButtonView = IPython.WidgetView.extend({
      
        // Called when view is rendered.
        render : function(){
            var that = this;
            this.setElement($("<button />")
                .addClass('btn')
                .click(function() {
                    that.model.set('clicks', that.model.get('clicks') + 1);
                    that.model.update_other_views(that);
                }));

            this.update(); // Set defaults.
        },
        
        // Handles: Backend -> Frontend Sync
        //          Frontent -> Frontend Sync
        update : function(){
            var description = this.model.get('description');
            description = description.replace(/ /g, '&nbsp;', 'm');
            description = description.replace(/\n/g, '<br>\n', 'm');
            if (description.length == 0) {
                this.$el.html('&nbsp;'); // Preserve button height
            } else {
                this.$el.html(description);
            }
            
            return IPython.WidgetView.prototype.update.call(this);
        },
        
    });

    widget_manager.register_widget_view('ButtonView', ButtonView);

});

Use setElement to set the view's element properly.
Use setElement to set the view's element properly.
