Ext.Button fire more than once when continually click

[yuncong8]

I create a window with two buttons "ok" and "cancle",when the "ok" button is click,it make panel submit user information and the window will close.
when you operate by mouse,everything is ok,but if the "ok" button is focused,then continually click "space" or "Enter",it send user information more than once.

the button should be disable for 20 millisecond, i think.