setVisible() in a callback (trying to fix a crash)

In a callback (from mouseDown, in a mouse listener), I am making some other component visible.  Unfortunately, the system crashes at some pointer after the callback is done.

What I think I need to do is to defer the setVisible until after the callback is done; but I don't see a way to do that other than the (probably) heavy method of using the CommandManager and invoking a command to execute from the msg queue.

Is there a better way?