title: Automatically alter button background and text appearance when pressed (like iOS)?
body: <p>In iOS, if I set a button's background to an image, when I press the button, the whole content of the button (including the text) will be shadowed. Can I achieve the same effect in Android, or do I have to use different images for different states? Also, even if I use different images for different states, how do I make the text also shadowed? A dirty way is to set a <code>OnClickListener</code> to the button and programatically shadow the text when pressed, but are there any other ways?</p>