Cannot set right monitor as primary in dual monitor configuration

[Jonathan]

XUbuntu displays the desktop icons and main taskbar (xfce4-panel) on the left monitor in a dual-monitor configuration, even if you go into the "display" control panel and mark the right-side monitor as "Primary Display."

Hardware: one monitor is connected to an HPE ProLiant Micro-server via its VGA port, and the other monitor is connected to a DisplayPort-to-VGA adapter that is in one of the Display Ports.

Operating system is Xubuntu 19.10:
$ lsb_release -rd
Description: Ubuntu 19.10
Release: 19.10

To reproduce: startup the computer. Go to the "display" app. Order the displays in the "display" app, then click on the right-side display, then click the switch icon next to "primary display" to toggle the right-side display to be primary.

Actual behavior:
The main taskbar (Xfce Panel) with the Whisker Menu remains on whichever monitor is designated as "left" in the Display app, even if the right display is designated as "primary."
Desktop icons display on the left monitor, even if the right display is designated as "primary."
Some programs open on the left monitor; others open on the right monitor.

This is very similar to the behavior documented in bug #1425000 which is marked as "won't fix," but the notes in bug #1425000 say that if the behavior is observed in xfce4, then a new bug-report should be opened. (Only difference is that in bug #1425000, which pertains to the Unity environment, programs always open on the left side. Here they may open on either monitor.)

Expected behavior:
Main taskbar (Xfce Panel) with the Whisker Menu should be on whichever display is selected as "primary" in the "display" app.
Desktop icons should, by default, display on whichever monitor is selected as the "primary" one.
Programs should open, by default, on whichever display is selected as "primary."

Package versions:
$ apt-cache policy xfce4-session
xfce4-session:
  Installed: 4.14.0-0ubuntu1
  Candidate: 4.14.0-0ubuntu1
  Version table:
 *** 4.14.0-0ubuntu1 500
        500 http://us.archive.ubuntu.com/ubuntu eoan/universe amd64 Packages
        100 /var/lib/dpkg/status
$ apt-cache policy xfce4
xfce4:
  Installed: (none)
  Candidate: 4.14
  Version table:
     4.14 500
        500 http://us.archive.ubuntu.com/ubuntu eoan/universe amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu eoan/universe i386 Packages
$ apt-cache policy xfwm4
xfwm4:
  Installed: 4.14.0-1
  Candidate: 4.14.0-1
  Version table:
 *** 4.14.0-1 500
        500 http://us.archive.ubuntu.com/ubuntu eoan/universe amd64 Packages
        100 /var/lib/dpkg/status

[Lyanidle-d (lyanidle-d)]

i am on debian stretch/xfce4 with triple monitor setup and no matter where i try to set the primary display, xfce ignores it. Windows/Applications are generally openend at the left screen, even though the primary screen is set to the middle. The only time they are not opened on the left is, when they are set to be opened on the screen where the cursor currently is. This behavior can't be correct.

xrandr output:

ebfe@home:~$ xrandr
Screen 0: minimum 8 x 8, current 5760 x 1080, maximum 32767 x 32767
DVI-D-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080 60.00*+
   1680x1050 59.95
   1440x900 59.89
   1280x1024 75.02 60.02
   1280x960 60.00
   1280x720 60.00
   1024x768 75.03 70.07 60.00
   800x600 75.00 72.19 60.32 56.25
   640x480 75.00 72.81 59.94
HDMI-0 connected 1920x1080+3840+0 (normal left inverted right x axis y axis) 598mm x 336mm
   1920x1080 60.00*+ 59.94 50.00 60.05 60.00 50.04
   1680x1050 59.95
   1440x900 59.89
   1280x1024 75.02 60.02
   1280x960 60.00
   1280x800 59.81
   1280x720 60.00 59.94 50.00
   1152x864 75.00
   1024x768 75.03 70.07 60.00
   800x600 75.00 72.19 60.32 56.25
   720x576 50.00
   720x480 59.94
   640x480 75.00 72.81 59.94 59.93
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080 60.00*+ 144.00 119.98 99.93 84.90 59.94 50.00 60.00 50.04
   1680x1050 59.95
   1440x900 59.89
   1280x1024 75.02 60.02
   1280x960 60.00
   1280x800 59.81
   1280x720 60.00 59.94 50.00
   1152x864 75.00
   1024x768 75.03 70.07 60.00
   800x600 75.00 72.19 60.32 56.25
   720x576 50.00
   720x480 59.94
   640x480 75.00 59.94 59.93
DP-5 disconnected (normal left inverted right x axis y axis)

[Olivier Fourdan (fourdan)]

Well, it's not a bug, it's on purpose...

"Primary" monitor is just a hint that the window manager is free to ignore, xfwm4 instead will map the window on the current monitor, i.e. the on where the mouse pointer resides (unless of course the client specifies a location using the standard ICCCM mechanisms).

[Lyanidle-d (lyanidle-d)]

Expected behavior: If application asks for 'primary monitor', XFCE opens window at primary, if asked for current monitor, XFCE opens at 'current monitor' (mouse pointer/focus).

Actual behavior: If application asks for 'primary monitor', XFCE opens always at left screen, if asked for current monitor, XFCE opens at 'current monitor'.

I'm sure you know better than me, but no matter if it's logically correct implemented as you say, it's not working in reality. I can't play a single game with XFCE on my 144hz gaming monitor that is in the middle of my 3 screens, because XFCE does not let it open anywhere else than on the left screen.

Finally I want to say: I am not alone here, XFCE german forum moderator said it's a bug, 3 different discord linux server agreed and told me it's a bug, and many other people aswell.

Please at least take this request to reconsider to at least add some option like in Openbox, where you can choose between open at 'current monitor' and open at 'primary monitor'.

The logic mistake I see here is: You want applications to always ask for "current monitor", but they ask for "primary" and XFCE does not allow me to set "primary", but just opens it at the left screen. Call it however you want, for me it's a bug.

[Olivier Fourdan (fourdan)]

(In reply to ebfe from comment #2)
> Expected behavior: If application asks for 'primary monitor', XFCE opens
> window at primary, if asked for current monitor, XFCE opens at 'current
> monitor' (mouse pointer/focus).
>
> Actual behavior: If application asks for 'primary monitor', XFCE opens
> always at left screen, if asked for current monitor, XFCE opens at 'current
> monitor'.

Sorry, that doesn't make much sense to me... On X11, applications do not ask to open on a monitor, they ask to place their window at any given location. AFAIK, the idea of "primary" monitor is alien to the application unless they decide to use that XRandr property to compute their location themselves...

> I'm sure you know better than me, but no matter if it's logically correct
> implemented as you say, it's not working in reality. I can't play a single
> game with XFCE on my 144hz gaming monitor that is in the middle of my 3
> screens, because XFCE does not let it open anywhere else than on the left
> screen.

Left screen is the one at (0,0) so maybe those applications specifies that location for their windows?

> [...]
>
> The logic mistake I see here is: You want applications to always ask for
> "current monitor", but they ask for "primary" and XFCE does not allow me to
> set "primary", but just opens it at the left screen. Call it however you
> want, for me it's a bug.

Applications do not ask for "monitor" *unless* they are fullscreen, in which case they may specify the monitor to use for fullscreen.

Where was a bug with the monitor indices (bug 9351) which is currently fixed, but I see no indication of what actual version of xfwm4 you are using...

But again, that would work only if that particular app maps its window fullscreen using the expected EMWH hints (_NET_WM_FULLSCREEN_MONITORS), only way to tell would be to provide the output of “xprop” on that window....

So please provide:

1. The output of “xfwm4 --version” on your system
2. The output of “xprop” taken from that window that you say always open on the left monitor

[Jonathan (jonathandl2)]

I have the same bug, which is documented as Ubuntu bug #1425000.
https://bugs.launchpad.net/bugs/1425000

The notes there say that if the bug affects xfce4, then a new bug should be filed, so I did:
https://bugs.launchpad.net/xfce4/+bug/1863788

Now I can't answer the troubleshooting question for the original reporter but, since I have the same problem, here's the output of "xfwm4 --version":
 This is xfwm4 version 4.14.0 (revision ed87ef663) for Xfce 4.14
 Released under the terms of the GNU General Public License.
 Compiled against GTK+-3.24.10, using GTK+-3.24.12.

 Build configuration and supported features:
 - Startup notification support: Yes
 - XSync support: Yes
 - Render support: Yes
 - Xrandr support: Yes
 - Xpresent support: Yes
 - Embedded compositor: Yes
 - Epoxy support: Yes
 - KDE systray proxy (deprecated): No

[Jonathan (jonathandl2)]

I have the same bug, which is documented as Ubuntu bug #1425000.
https://bugs.launchpad.net/bugs/1425000

The notes there say that if the bug affects xfce4, then a new bug should be filed, so I did:
https://bugs.launchpad.net/xfce4/+bug/1863788

I can't answer the troubleshooting question for the original reporter but, since I have the same problem, here's the output of "xfwm4 --version":
 This is xfwm4 version 4.14.0 (revision ed87ef663) for Xfce 4.14
 Released under the terms of the GNU General Public License.
 Compiled against GTK+-3.24.10, using GTK+-3.24.12.

 Build configuration and supported features:
 - Startup notification support: Yes
 - XSync support: Yes
 - Render support: Yes
 - Xrandr support: Yes
 - Xpresent support: Yes
 - Embedded compositor: Yes
 - Epoxy support: Yes
 - KDE systray proxy (deprecated): No

[Launchpad Janitor (janitor)]

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

[Sean Davis (bluesabre)]

Based on the latest upstream comment: https://bugzilla.xfce.org/show_bug.cgi?id=14610#c12

> @gwillem: Luckily you show the popup from display settings which confirms the suspicion: you need to configure your panel, desktop and notifications to show on primary (this is only an option, not the default).

> Go to each respective settings dialog and tick the appropriate option.

This is working as designed. Marking the ticket as closed.