>I need to add an auto logoff feature to an existing application. This is the standard "log off the user after x minutes of inactivity". I can think of several ways to implement this, but before I begin, I'm interested in hearing how others have done this.

We did this by using a timer at the client side constantly checking for MROW()/MCOL() and LASTKEY() change. when they do not change for xx time, close the app. This will close APP when it is not active though. When yo want to close it only when user does not touch computer, (like for screen saver), just use Windows API functions to get the mouse position.