I thought the same about the shortcomings of needing code in any form that uses the control.
I tried the 'StaysOpen' idea on a simple popup and (apart from the need for the extra click which you witnessed) it worked consistently so maybe your control could be tweaked somehow.

Another possiblility (not tested):
Create a subclass of ElementHost to hold the WPF control. In its constructor you could then use FindForm() to get a reference to the WinForm and hook up the Forms Move event (etc) to code in the WPF control to close the popup.

The problem with that is that even if it solves for Winforms the problem still exists in a WPF environment. I'm not sure what the advantage of using the CreateRootPopup as per the example is - have you tried the simpler approach of just using your control as content of a popup? Of course, there may be no advantage there either - but at least it's simpler to comprehend :-}

Regards,
Viv

I decided to rewrite my main application as a WPF application. I don't have all that much invested in libraries yet. And I tend to do a few scrap it all and rewrites when I'm learning. I think this is my third, so I'm getting close :-)

Once that's done, I should be able to drill down to the form or use the application.current.windows collection to get the event I need.

The element host would be sweet for adding some WPF to a winform app. But if I'm going to go all WPF then I might as well go WPF from the ground up.

Thanks for all your help on this! It is greatly appreciated.