code: function(sourceEditMode) {
          var me = this,
              iframe = me.iframeEl,
              textarea = me.textareaEl,
              hiddenCls = Ext.baseCSSPrefix + 'hidden',
              btn = me.getToolbar().getComponent('sourceedit');
  
          if (!Ext.isBoolean(sourceEditMode)) {
              sourceEditMode = !me.sourceEditMode;
          }
          me.sourceEditMode = sourceEditMode;
  
          if (btn.pressed !== sourceEditMode) {
              btn.toggle(sourceEditMode);
          }
          if (sourceEditMode) {
              me.disableItems(true);
              me.syncValue();
              iframe.addCls(hiddenCls);
              textarea.removeCls(hiddenCls);
              textarea.dom.removeAttribute('tabIndex');
              textarea.focus();
              me.inputEl = textarea;
          } else {
              if (me.initialized) {
                  me.disableItems(me.readOnly);
              }
              me.pushValue();
              iframe.removeCls(hiddenCls);
              textarea.addCls(hiddenCls);
              textarea.dom.setAttribute('tabIndex', -1);
              me.deferFocus();
              me.inputEl = iframe;
          }
          me.fireEvent('editmodechange', me, sourceEditMode);
          me.updateLayout();
      }
docs: Toggles the editor between standard and source edit mode.
  @param {Boolean} [sourceEditMode] True for source edit, false for standard