[Pharo-dev] Detect when Pharo loses focus

Hi guys, I am trying to detect when a user switches her focus from Pharo to another app. In short I’d like to know when the user switches (i.e., atl+tab) from the Pharo application to another application, losing focus from the development. I looked into Morphic and I was able to tell when the mouse goes outside the Pharo window. Unfortunately this technique does not work when the user uses alt+tab to switch to another app, since the last mouse event is not outside the Pharo window. Any suggestion where to look? Thanks in advance, R