I need a message pump that doesn't mess up my open window

Question

My application (the bootstrap application for an installer that I\'m working on needs to launch some other applications (my installer and third party installers for my installer

Answer 1

When you say that window and menu handles seem to be being freed, do you mean that you've got actual HWND and HMENU values that no longer seem to work, or have you got MFC CWnd* and CMenu* variables that fail?

If the latter, the problem is most likely that you're getting the CWnd* pointers by calling CWnd::FromHandle() (or CMenu::FromHandle()) somewhere (or calling something that calls them), and OnIdle() is discarding them.

The underlying reason is that MFC maintains a map from window (or menu, etc.) handles to CWnd* objects in the system. When CWnd::FromHandle() is called, it looks for a match in the map: if one is found, it's returned. If not, a new, temporary CWnd is created, added to the map, and returned. The idea behind OnIdle() is that when it's called all message processing is done, so OnIdle() discards any of these temporary CWnd objects that still exist. That's why the CWnd::FromHandle() documentation warns that the returned pointer may be temporary.

The "correct" solution to this is to not hang onto the CWnd* pointers returned from CWnd::FromHandle(). Given the simplicity of your application, it might be easier to just remove the call OnIdle(): this shouldn't have any negative effects on an installer.

Of course, this is all something of a guess, but it sounds plausible...