Invisible dialogs

[Love Nystrom]

I've come across a whopper size bug, likely somewhere in USER or GDI (in 
r54606).

If you switch app while you have a modal dialog open, and the new window 
covers that dialog,
then when you come back that dialog is invisible, but it's window proc 
still active, meaning
you have no way to back out of it, and you have to kill the app with 
taskman (if you can).
I would nominate this a real blocker, it's just too embarrassing to release.

I'll try to figure a repeatability and file a bug, and I'd recommend 
that USER and GDI
devs heed Alekseys request for feature freeze and roll up their sleeves 
on this one.

Best Regards
// Love