Posts: 1945 from 2003/3/5
This comes down to how you handle IDCMP_MOUSEBUTTONS in MUIM_HandleEvent. Looks like you handle and eat them even when the click is outside of the displayed area of your object.
You can see it works just fine in the System Preferences if you open them on a low resolution screen. It likely works for you on MUI 3 since its routing of events is a bit different.