xfce4-display-settings "Primary display" option does not work properly

[Leonardo Müller]

I have a setup with the notebook screen and a external monitor above the notebook. If I position them using xfce4-display-settings, the monitor with the xfce4-panel and the wallpaper for the first screen is always the external monitor, as it's above the notebook screen. The option to set the "Primary display", which should allow users to change which screen is the primary, do not work properly.

While the setting does not work properly, it has effects but some are negative. The only software I've seen that honors the option properly is LibreOffice splash screen. The screen the program appears after the splash depend from on which screen the mouse cursor is (as the other applications do).

Another application that detects the option is xfce4-panel, but this is only partial: the panel is always located on the leftmost or topmost monitor, but if the topmost monitor is not the "Primary screen", then the desktop icons ignore the panel and are covered by the panel. Image showing this: https://i.imgur.com/Y5WOF3I.png

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xfce4-settings 4.12.3-0ubuntu1
Uname: Linux 4.16.6-041606-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: XFCE
Date: Fri May 4 15:45:01 2018
InstallationDate: Installed on 2017-06-13 (324 days ago)
InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: xfce4-settings
UpgradeStatus: Upgraded to bionic on 2017-10-20 (196 days ago)

[Theo Linkspfeifer (lastonestanding)]

Some applications may not support the primary option yet, so I do not think that this a bug in xfce4-settings which just enables it (equally to xrandr --output <display> --primary).

https://bugzilla.xfce.org/show_bug.cgi?id=8328

If possible, please test with Xubuntu 18.10 (dev release).

[Leonardo Müller (leozinho29-eu)]

The issue seems like it's really not xfce4-display-settings fault, but xfce4-panel and xfdesktop that do not respect the monitor chosen as the primary one.

Using Xubuntu 18.10, if I chose the Primary Monitor as the bottom monitor the desktop icons are partially hidden under the panel and the panel is still at the topmost monitor, even if I chose the bottom monitor as the Primary.

It seems like xfce4-panel and xfdesktop (not sure on this one) don't deal correctly with the Primary display setting.

[Theo Linkspfeifer (lastonestanding)]

Possibly related reports:

https://bugs.launchpad.net/ubuntu/+source/xfce4-panel/+bug/1770205
https://bugzilla.xfce.org/show_bug.cgi?id=14630

It suggest to contact the Xfce devs and try to debug this issue.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Elbarbudo (patricearnal)]

I got a similar problem : Notebook and external monitor.

When I put the monitors "side by side" the "Primary monitor" setting works OK.
BUT if I place the secondary monitor over the laptop, the "primary monitor" setting is ignored and the above monitor is always primary, whichever setting I choose

BTW I did not succeed to find how contact Xfce devs or buglist