Changing resolution

I'm trying to make my application change the resolution when activated (become the active task) and restore the original resolution when deactivated (using normal termination, tab key usage, click on other app on the task bar etc..)

I did not find any way to do this except using an ActiveX dll written in VB6 and is referenced by the .Net project.

The calls to the dll function are located in the Active & Deactivate events of each form.

The problem is sometimes when user click on another app in the task bar, the resolution is changing but my application remains in from of the desktop (even not active).

Can someone help?

In addition,
Is there a better way to change the screen resolution?

Thanks