Alan Kay <Alan.Kay at squeakland.org> writes:

> On any morph, do a cmd-click (alt-click on PC) to bring up its halo 
> of handles. Press down on the red handle to get a menu and look near 
> its bottom for "extras". Slide down there and look at its popout for 
> "add new mouse action". Releasing on this will pop up a dialogue box 
> in which you can type your Smalltalk expression.

I like that. But once I have a custom mouse up expression, the button
can only be moved via the halo, not by just dragging it.