ImageButton doesn't honor the transparency of my android:src png. My
src image is a rounded rectangle, with the remaining portion of the
bounding rectangle set to be transparent. When the button is
displayed, what should be transparent is a dark shadowy color. The
images I'm using are OK, and display the proper transparency when
shown in a browser. android:background="@android:color/transparent"
doesn't have any effect. Or do I need to subclass ImageView directly
to get the desired handling of the src image transparency?