.net - Keeping a Windows application on top of other windows and in focus - always

Question

I am creating a kiosk application and I want to ensure it is always, no matter what, on top of other Windows applications and the Windows task bar.

I am already blocking Windows keyboard commands (alt-tab, etc) but there are still situations that could cause an application to launch and steal the screen.

Is it possible to hook into Windows from .NET and continually test whether the application has focus and is on top, and if not then give it focus and make it on top?

Answer 1

I've actually worked on a production kiosk (it was Windows 2000, however). The solution was to run our application as the shell. You accomplish this in part by replacing Explorer.exe with your application in the Shell value at:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogon

See here for some more information.

Now, we did have a secret (err... obfuscated) way to shut down our app. Then we would bring up Task Manager (Ctrl-Shift-Esc) and select File/New Task to run Explorer.exe to bring up a shell right then and there.

As an aside, when you work on a system like this, you naturally become very very proficient with the keyboard and all that it means to use keyboard shortcuts in Windows because you will likely not have a convenient way or place to put a mouse.