title: TinyMCE add item to context menu
body: <p>I want to add a new menu item to TinyMCE's context menu, and perform a command when the user clicks it, so far i have this, which is not working:</p>
  
  <pre><code>tinyMCE.init({
  ...
  
  setup : function(ed) {
      ed.onContextMenu.add(function(ed, menu) {
          menu.add({title : 'Menu 1', onclick : function() {
              alert('Item 1 was clicked.');
          }});
      });
  }
  </code></pre>
  
  <p>The code above throws an error saying "menu.add is not a function", if i remove the menu.add stuff and place a console.log(menu), it returns "contextmenu" upon opening the context menu.</p>
  
  <p>What would be the right way to add an item to the context menu ? Preferably without having to modify the plugin itself. Thanks in advance.</p>