How to track the time users spend on web client screens - FSM

I’m not aware of a way to accomplish this with OOB functionality.  To do so via client scripts, you would need some new events to hook into - namely LostFocus and/or CloseScreen events for the screen.  Even so, this may be difficult as the use could have several screens open on different tabs and conceivably you would only want to track their time while they were actively using a certain screen.  Likewise, they could have multiple tabs open for the same screen, which would further complicate things.

Easy enough to track the date/time that a particular screen instance is opened or navigated to, but not possible when closing or navigating from.