focus( Boolean selectText, Boolean/Number delay ) : Ext.Component 
试着将焦点放到此项。Try to focus this component. 
试着将焦点放到此项。Try to focus this component. 
参数项： 
selectText : Boolean 
（可选的）true的话同时亦选中组件中的文本（尽可能）。(optional)If applicable, true to also select the text in this component 
delay : Boolean/Number 
（可选的）延时聚焦行为的毫秒数（true表示为10毫秒）。(optional) Delay the focus this number of milliseconds (true for 10 milliseconds) 
返回值： 
Ext.Component 
this