I'm using an MFC Doc/View structure. When the menu drops down over the draw screen (CView window), the region under the menu area is invalidated and a WM_PAINT message is issued.
CMenu::TrackPopupMenu also invalidates the region. I thought Windows managed an offscreen bitmap to automatically handle this.
I use CS_SAVEBITS , but that doesn't seem to help. Perhaps I do not have the right combination of flags.
Can you help?
cs.lpszClass = AfxRegisterWndClass( CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW | CS_SAVEBITS, AfxGetApp()->LoadCursor(IDC_NULL_CURSOR), (HBRUSH) (COLOR_WINDOW +1));