Comment 6 for bug 1612087

Still reproducible I'm afraid. In fact, it appears to have gotten worse: while dragging the screens around it would sometimes not even register that I had released the mouse button and would keep dragging the screen around. Then at one time, it put the 3rd screen almost entirely underneath the second. I've made a video of it: https://www.youtube.com/watch?v=BIhRCDVYlkA (you'll have to turn up the audio to hear the mouse clicks).

The closest I got was this:

eDP1 connected 1920x1080+0+1 (normal left inverted right x axis y axis) 350mm x 190mm
DP2 connected 1920x1080+3842+1 (normal left inverted right x axis y axis) 530mm x 300mm
HDMI1 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 530mm x 300mm

As you can see there's still a 2 pixel gap between DP2 and HDMI1

It looks fine in the lock screen, by the way.