Hi all, finally got it. Turned out to be related to the host window/menu work, the window index slot needed to be set to 1 if 0. Sigh... Attached is a change set that installs the new logic into a recent Pharo image. I'm not sure if and how we can get the install into a package load, but this version is for the adventurous types anyways :-) A few remarks about the new sensor architecture (need to put this into the class comments). First what's not changed, which is the morphic side. HandMorph still polls for nextEvent and also all old polling methods are still supported and heavily used in the image. Basically the input event handling has been split into two parts: one event fetcher and event handlers. The event fetcher fetches events from the even and currently still polls. Next step will be to get the input semaphore signaling working. The event fetcher then signals the event to all registered event handlers. In the current version there are two: the new morphic sensor and the user interrupt handler. Events currently are handled multiple times (rather their copies), we might need to change that later. There needs to be some work done on how the user interrupt handler works, I had some problems with launching the debugger, but that might have been a problem in my development image. It would be helpful though, if the VM would provide information about the interrupted process as it does (or should do?) for the low space watcher. So much for now, questions welcome and happy testing :-) Michael