Hi, I’m pretty sure I tracked down this bug well enough to post about it. It’s a bizarre one.
I created a plug-in with a few sliders, setting all sliders to “no text box”. The result was some rather ugly behavior with mouse-up and mouse-over. In short, it was totally broken. The fix was to set any one of the sliders to have a text box, and the problem magically went away.
So, all sliders no text box -> messed up mouse behavior. Any one slider slider w/ text box -> normal behavior.
The issue was in Cubase 5, Logic 8, and Max 5. It did not happen in AULab.