General breakage with multiple monitors (affecting kde's yakuake and spectacle)

Submitted by kez..@..il.com

Assigned to xf86-video-ati maintainers

Link to original bug (#111581)

Description

Hi, I've been sent here from the kde bug tracker, here's the original issue with all the info https://bugs.kde.org/show_bug.cgi?id=411652

video: https://youtu.be/zikzg5cDIrs

The two major things are:

1. spectacle's "rectangular region" mode is shifted to the left, and I can't screenshot the left part of the desktop
   
2. yakuake doesn't show up on a monitor, or, with two monitors, it shows but with a smaller / wrong width
   

This seems to also glitch part of some applications, for example QtCreator works "better" on the left monitor, on the rightmost one it tends to glitch and not update the screen / render some panels with wrong size

some times if I move a windows in the rightmost monitor, the cursor teleports to the left one while the windows remains on the right


STEPS TO REPRODUCE
1. attach more than one monitor (tested with 2 and 3 4k monitors)
2. admire the breakage

I can reproduce this with another clean user, so it shouldn't be a configuration issue

ArchLinux with everything up to date and RX480