I was using a Classic filemaker application that required a lot of tedious mouse clicks, so decided to automate this using QuicKeys X2. After much configuration I got the macro to work. Unfortunately this long running macro hogged my Mac while it worked, given that it replayed my mouse clicks and kept grabbing the pointer and switching the application in use.
I started to wonder how QuicKeys would behave when running from another user that I had switched away from. I figured that it would behave like iTunes or iChat and stop while switched away or would run the macro in the current user space. So, I set my macro running and switched to a new user. Nothing odd seemed to be happening in the new user I was working with. The mouse behaved itself. I then switched back and found my macro had been working all the time.
This is an excellent way of pushing a QuicKeys user actions macro into the background while you get on with something else. This tip was done in 10.3.3
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040418075718998