Toggle left panel in Odoo 8 and add a widget button in menubar

toggle_menu.js

openerp.web.Menu.include({                                                                                                                                                                                       
    /**                                                                                                                                                                                                          
     * Enable left menu to be toggled                                                                                                                                                                            
     */                                                                                                                                                                                                          
    show_nav_bar: function() {                                                                                                                                                                                   
        var nav_bar = $('.oe_leftbar');                                                                                                                                                                          
        nav_bar.css('display', 'table-cell');                                                                                                                                                                    
    },                                                                                                                                                                                                           
    hide_nav_bar: function() {                                                                                                                                                                                   
        var nav_bar = $('.oe_leftbar');                                                                                                                                                                          
        nav_bar.css('display', 'none');                                                                                                                                                                          
    },                                                                                                                                                                                                           
    bind_menu: function() {                                                                                                                                                                                      
        var self = this;                                                                                                                                                                                         
        self._super();                                                                                                                                                                                           
        var toggle_button = $(document.createElement('span'));                                                                                                                                                   
        toggle_button.append('☰');                                                                                                                                                                         
        toggle_button.css('color', 'white');                                                                                                                                                                     
        toggle_button.css('float', 'left');                                                                                                                                                                      
        toggle_button.css('cursor', 'pointer');                                                                                                                                                                  
        toggle_button.css('padding-top', '5px');                                                                                                                                                                 
        toggle_button.css('padding-right', '10px');                                                                                                                                                              
        toggle_button.click(function(e){                                                                                                                                                                         
            e.stopImmediatePropagation();                                                                                                                                                                        
            var nav_bar = $('.oe_leftbar');                                                                                                                                                                      
            if (nav_bar.css('display') == 'none') {                                                                                                                                                              
                self.show_nav_bar();                                                                                                                                                                             
            } else {                                                                                                                                                                                             
                self.hide_nav_bar();                                                                                                                                                                             
            }                                                                                                                                                                                                    
        });                                                                                                                                                                                                      
        $('#oe_main_menu_placeholder').prepend(toggle_button);                                                                                                                                                   
    },                                                                                                                                                                                                           
    menu_click: function(id, needaction) {                                                                                                                                                                       
        var self = this;                                                                                                                                                                                         
        self._super(id, needaction);                                                                                                                                                                             
        self.show_nav_bar();                                                                                                                                                                                     
    },                                                                                                                                                                                                           
                                                                                                                                                                                                                 
});