[Pharo-project] Event history question

Hi all, the event handling rewrite slowly starts to work :-) I'm currently fighting the parts where polling is used (like moving a window), but more on that later. The question I have is about user interrupt handling. I'm a bit confused and don't remember the history there: was there first an interrupt semaphore that then was abandoned or was it introduced but then not supported on some platforms? Or phrased differently: do we want user interrupt go through an interrupt semaphore or rather handle it on the image side? Michael