ExtJS setting focus in a window

I needed to set the focus to a field in an Ext.Window that contains a FormPanel. Turns out to be really simple, even though it took me awhile to find it…. use the defaultButton config on Ext.Window. It is poorly named, b/c it can be any component, not just a button.

Ext JS 4 Update

Looks like defaultButton is gone and now Ext.window.Window has the more helpfully named field “defaultFocus”.  And, straight from the docs:

Specifies a Component to receive focus when this Window is focused.

This may be one of: