mmands.addCommand({
      name: 'undoCommand',
      bindKey: {win: 'Ctrl-Z',  mac: 'Command-Z'},
      exec: function(editor) {
        editor.getSession().getUndoManager().undo(false);
      },
      readOnly: false
  });
  editor.commands.addCommand({
      name: 'redoCommand',
      bindKey: {win: 'Ctrl-Shift-Z',  mac: 'Command-Shift-Z'},
      exec: function(editor) {
        editor.getSession().getUndoManager().redo(false);
      },
      readOnly: false
  });
  editor.loadUrl = function(filename){
  