I want to embed a SimpleButton in a larger RectangleMorph. If I add
the Button as submorph to the Rectangle, the Button is always on
top. #goBehind does not seem to change this.

Thus the Button responds to mouse events. I want the Button to be
"dead" though, i.e. I want to be able to drag the twosome from the
Button. 

I could turn things around and add the rectangle to a Button.

I could subclass the Button and let handlesMouseDown: return false.

What other options do I have ?