Esc.PopupMenu.prototype._createPopup=function(){
var popupDiv = $('<div tabindex=1></div>'); //创建div
popupDiv.appendTo(this._owner.element); //将div加span
var _popup=popupDiv[0];
_popup.hide=function(){
popupDiv.hide();
},
_popup.show=function(){
popupDiv.show();
popupDiv.focus();<span style="white-space:pre"> </span>//让div得到焦点
};
popupDiv.blur(function(){
popupDiv.hide();
});
return _popup;
}