Rob: Thanks for mentioning the crossposting on stack overflow. The specific requirements were mentioned in my first post: I need the component that would be the source for a mouse event. There are a lot of ways that don't work, I'm looking for one that does.
Below is my current approach. (Developed after I posted the original question.) I'd like to find one that is simpler and that deals correctly with the event mask. For anyone who is tempted to use the following code, I'd caution that it is not thoroughly tested.