Joey -

I do not understand your question about designer classes or
typeconverters. This is a usercontrol with a couple of scroll bars, and
a custom client area paint override.

I really can't post code, but I can say I override a lot of mouse and
other OnXXX handlers. I always invoke the base-class on-handlers in my
override. The only OnXXX handler that I have made sensitive to being in
design mode is the paint routine, in which I use a simple paint that
does not utilize the runtime state of the object. Maybe there are more
on-handlers being called in design mode than I realize?

I think I need to explore the docs more for techniques to debug
design-time behaviour.  I don't get any error messages, which may give
some hints, the damn thing just disappears, and only half-way.

Thanks for giving some hints/direction here.

Best regards - Lee

Thanks Cheese -

I'll not focus some much time to trying to mitigate something that is a
problem in the platform.

Best regards - Lee