[android-developers] widget buttons/images changing the layout

I can write a widget with a Button or ImageButton and assign a StateDrawable as background or sourcein order to make an effect when you click it. Besides that I have problems with the side of each button, my main problem is this: how do I change the StateDrawable if I want to change the image of the button from the AppWidgetProvider but still want to preserve the click effect like a StateDrawable. The power control widget in Android does things like that. Help would be very appreciated, I've tried so many things already, but nothing works.