DirectX / Windows: Unable to focus on task manager when force-closing application

Question

This question might show a fundamental misunderstanding of DirectX programming in Windows, but I'm having a bit of an issue I can't figure out. My program, when running in full screen, sometimes gets in a weird state and I have to force close the app (CTRL+ALT+DEL).

The problem is that when I hit CTRL+ALT+DEL, task manager appears, but I can't use the mouse; the keyboard works at first, but if I click on the Task Manager window with my mouse, it loses focus and I can no longer regain focus. The app also does not minimize itself (Windows app programming issue?)

Is it possible that my app is stealing the exclusive possession of the mouse? I am using DirectInput, but the mouse input is not handled by the app at all. Furthermore, this problem only happens when running the app fullscreen. If I run it in a Window, everything is fine.

If it matters, the tools I'm using are MS Visual Studio 12, Windows 8, and DirectX 9.

Answer 1

The solution to this was to unacquire all input devices and stop the rendering routines when the focus was lost from the application. I just set the app to keep track of whether or not it has focus, and to adjust the value appropriately in the Windows message pump for the appropriate messages. Specifically, I set focus to "off" when I receive the following messages:

WM_SIZE (when wParam = SIZE_MINIMIZED), WM_KILLFOCUS, WM_ENTERSIZEMOVE, and WM_ENTERMENULOOP

I set focus back on for the following messages:

WM_SIZE (all other cases), WM_SETFOCUS, WM_EXITSIZEMOVE, WM_ACTIVATEAPP with wParam set to true, and WM_EXITMENULOOP

WM_KILLFOCUS is adequate to solve the problem for ALT-CTRL-DELETE-ing out of the application.