Preventing user from using ALT+TAB from an external app

Hi,

would you know how to prevent a user from doing this?
Basically: I have a VB app that launches an external app. I can get the handle of the new app. The new app is launched full screen. I would like to prevent the user from either:
1) use Alt Tab to switch to an other app
2) allow it but then launch a msgBox asking user if he would like to exit the app
3) Allow it but perform a couple of internal function and be informed when user comes back to the app again.

Any idea for 1) , 2) or 3)?

To do this from the application itself wouldn't be too much trouble. To do this from another application (your VB app) would be much more complex, but as with everything, ultimately possible.

One approach would be using GetForegroundWindow in a tight loop.