Using GpgOL 2.0.6 in OL 2016 Plus (16.0.4549.1000) 64-bit under Windows 10 Enterprise 64-bit (Release 1607).
Sometimes when I sent a message signed with GpgOL, after the "Compose" window closed, there would be "remains" of said "Compose" window. It looks like a "skeleton" window. This window can't be closed with "Esc," but it can be closed with the "close" icon in the top-right corner.
I don't know which more details to provide. Please guide me what else I could provide to support tracking this down.