Mouse drag + external panels + separate display = not working

Mouse drag (on sliders for example) not working on external panels when on a
separate display. This is true of default or 3rd party panels.

I see no issue with mouse dragging with pop-out screen on external windows.

It seems hit or miss here…
Main display is windowed on a 3440x1440 display and secondary is 2560x1440

Hello @runshotgun , I was able to reproduce this behavior and this issue will
be investigated. I will let you know when I know more Thanks for reporting
this (and for the repro video / infos), Regards, Boris

Just tested on SU12, still an issue