How to monitor focus changes?

Question

Well Sometimes I am typing and very rarely it happens that something steals focus, I read some solution (even a VB watch) but they don\'t apply to me. Is there any windows-w

Answer 1

You can monitor focus changes with a hook. SetWindowsHookEx(), using the WH_SHELL hook gets it done. The callback gets the HSHELL_WINDOWACTIVATED notification.

This isn't easy to get going, particularly in a managed language since it requires a DLL that can be injected. Nor could you reliably tell the difference between an intended focus change or a process shoved the window and stole the focus. Which Windows tries to prevent but there's a backdoor called AttachThreadInput() that fools that code.

It is never difficult to tell what process does this. After all, it tried to activate one of its windows. Uninstalling that program is the simple and best fix.