Ext 中跟着浏览器的变化window居中

Ext 中随着浏览器的变化window居中

//** Ext.ux.CenterWindowPlugin?? **//
Ext.ux.CenterWindowPlugin = function(){
??? this.init = function(win) {
???????? Ext.EventManager.onWindowResize(function(){
???????????? win.center();??????????
???????????? });???????
???????? }???
};