title: How to remove ImageButton's standard background image?
body: <p>In <code>ImageButton</code> I want to remove the standard button background image. In <a href="http://developer.android.com" rel="noreferrer">http://developer.android.com</a> it is said, that one must define his\her own background image or set the background color to be transparent. I tried to set a black background, but it didn't make any effect...</p>