关于ExtJS4.1:快捷键支持的问题(2)

/// <reference path="Ext/ext-all-debug-w-comments.js" />

 Ext.onReady(function () {

     var viewport = Ext.create('Ext.container.Viewport', {
         layout: {
             type: 'vbox',
             align: 'stretch'
         },
         padding: 10,
         items: [{
             xtype: 'panel',
             id: 'panelA',
             title: '快捷键测试A',
             tbar: [{
                 text: '添加(F2)'
             }],
             frame: true,
             flex: 1,
             html: '您好，这里显示的表格或表单 。',
             autoEl: {
                 tag: 'div',
                 tabindex: 0
             }
         }, {
             xtype: 'panel',
             id: 'panelB',
             title: '快捷键测试B',
             tbar: [{
                 text: '添加(F2)'
             }],
             frame: true,
             flex: 1,
             html: '您好，这里显示的表格或表单 。',
             autoEl: {
                 tag: 'div',
                 tabindex: 0
             }
         }]
     });

     Ext.create('Ext.util.KeyMap', {
         target: 'panelA',
         key: Ext.EventObject.F2,
         fn: function (key, ev) {
             alert('添加A');

             ev.stopEvent();

             return false;
         }
     });

     Ext.create('Ext.util.KeyMap', {
         target: 'panelB',
         key: Ext.EventObject.F2,
         fn: function (key, ev) {
             alert('添加B');

             ev.stopEvent();

             return false;
         }
     });

     Ext.get('panelB').focus();
 });

实际结果
打开浏览器后直接按F2有效果了；打开浏览器后用鼠标点击A或B后再按F2就有效果了。