I have a dialog that updates a static control with a drawing thumbnail in OnInitDialog. This works fine on Windows XP but the initial update fails on Windows 7. Has something changed here? Once the dialog is displayed on Windows 7, any updates cause the thumbnail to redraw properly, but the first one fails...
Further investigation reveals that it is 'Aero' theme on Windows 7 causing the problem, if I switch to the 'Classic' theme, the problem goes away.
Any idea how to handle that?
I think the DWM is getting out of synce with the screen in some fashion, but
I can't find any way to kick the DWM into action on opening the dialog, perhaps I need to look through the DWM api...