Triple-monitor setup screens not lining up

[Christoph]

I'm running Loki on a Dell Studio 9550 with three monitors in total, all on a 1920x1080 resolution. Whenever I start up the computer, the monitors do not appear to line up properly. The leftmost 3 pixel columns of the middle screen are repeated on the rightmost side of the left screen. There also appears to be a gap of about 5 pixels between the middle screen and the right screen; I can move stuff 3 pixels to the right from the edge of the screen before it starts appearing on the right screen.
Opening arandr and rearranging the monitors there fixes it, until I reboot or use the Displays control panel to rearrange the monitors there.

Running xrandr gives me the following geometries:
eDP1 connected 1920x1080+3+0 (normal left inverted right x axis y axis) 350mm x 190mm
HDMI1 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 530mm x 300mm
DP2 connected 1920x1080+3845+0 (normal left inverted right x axis y axis) 530mm x 300mm

If you look at the x offsets you'll see that eDP1 is offset by 3 pixels, overlapping HDMI1, and that there is a 5 pixel gap between HDMI1 and DP2

[Zisu Andrei (matzipan)]

The bug where your settings are not remembered after a restart is covered in bug #1493707

[Christoph (christoph-cantillon)]

Actually the settings are remembered, sort of. The order of my monitors is preserved (on first boot, the monitors were in a different order than they are now), it's just that there's a small error on the coordinates.

[Cassidy James Blaede (cassidyjames)]

Christoph, there was recently a massive reworking of the Displays plug. Can you make sure you're completely up to date and then reconfirm this bug?

[Cassidy James Blaede (cassidyjames)]

You may also need to move the displays around in the plug, apply, then move them to how you'd like them. After that, let me know if this is still reproducible.

[Zisu Andrei (matzipan)]

Hey Cass, Felipe's rework seems to not fix the bug where it switches to default settings after a reboot, so I'm not sure it might help in OP's case.

[Christoph (christoph-cantillon)]

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.

[Christoph (christoph-cantillon)]

Also just figured out that it resets to the wrong layout every time I unlock the session.