Background "Spanning screens" option does not work

Submitted by Alistair Buxton @ali1234

Assigned to Eric Koegel

Link to original bug (#14868)

Description

Created attachment 8103 screenshot showing the bug

Not really much to say here. The "spanning screens" option doesn't work. The image is scaled to fit the primary monitor and the other monitors continue to show whatever background is set for them. See screenshot.

Attachment 8103, "screenshot showing the bug":

Version: 4.13.2

Andre Miranda @andreldm said:

It works here. I've pushed a couple of fixes related to backdrop, can you try with git master?

Theo Linkspfeifer said:

I can confirm this bug after assigning the 'primary' status to my second monitor.

Theo Linkspfeifer said:

The "Spanning screens" menu entry is visible for the primary monitor, but it only works for the monitor which was the primary one during xfdesktop launch.

Theo Linkspfeifer submitted a patch:

Patch 8763, "quick diff":
bug14868.diff

Andre Miranda @andreldm submitted a patch:

Sorry for the late reply, I'm running xfdesktop 4.14.1 and it works for me (see screenshot). Am I missing something?

Patch 9097, "dual-monitor-screenshot.png":

Theo Linkspfeifer said:

Look at the Desktop Settings window for each monitor and check which one allows you to set the "Spanning screens" style. Then change the primary monitor and check again.

Alistair Buxton @ali1234 said:

Confirming that xfdesktop doesn't know when the primary monitor changed.

Steps to reproduce:

1. Have background spanning working.
2. Open displays and change the primary display. (Nothing happens yet.)
3. killall xfdesktop (it will restart, and now spanning won't work.)
4. Change the primary desktop back to what it originally was. (Again, nothing happens yet.)
5. killall xfdesktop (it will restart, and now spanning works again.)

There seems to be a race condition during login if your chosen primary monitor is not the default. Sometimes xfsettings will change the primary after xfdesktop has initialized, and then your background settings are invalid and spanning doesn't work right.

Alistair Buxton @ali1234 said:

So we can make xfdesktop smarter about primary monitor changes and that is probably a good thing but... why does it matter what the primary monitor is? It should not care. It should stretch the wallpaper over all monitors regardless of which one is primary.

Theo Linkspfeifer commented on patch 8763:

I agree that the option should be a global one.

After testing my patch again I noticed that it does not work 100% properly, so I will mark it as obsolete.

Andre Miranda @andreldm said:

Thanks for the clarification, now I can reproduce the bug. I also agree that "spanning screens" should be independent of the primary monitor, although I'm not sure how the UI should be changed, maybe move this option to a checkbox.

I also missed seeing this option until i found this bug, as I never saw the entry when i set my laptop and external monitor setup to extended, as i made the external monitor as the primary screen.

Having it in the dropdown list seems to be fine. Windows has it in the list as well.

mentioned in issue #105

Yes, this is indeed related to #105 and is reproducible in Xfce 4.16.

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