I just discovered this strange MDI behavior last night. I'm not entirely sure what prompted it, but I noticed it just after attempting to DCC SEND a wav file to someone.
Note the two MDI window icons, and the two MDI min/max/close icon sets. The extra icons all function normally, accepting clicks, showing menus, etc... just too many of them.
I don't know if I can reproduce this behavior. Just wanted you to know about it.
This is Windows 7 Pro 64.