Bug 503864

Summary:	On X11, with a mixed-DPI dual-screen system (1920x1080 and 1680x1050) the wallpaper images should appear centered on one head and not run over to the other
Product:	[Plasma] plasmashell	Reporter:	george
Component:	Image & Slideshow wallpaper plugins	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED UNMAINTAINED
Severity:	minor	CC:	i, nate, notmart, qydwhotmail
Priority:	NOR	Keywords:	multiscreen, X11-only
Version First Reported In:	6.3.5
Target Milestone:	1.0
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	attachment-2507129-0.html attachment-2550870-0.html attachment-2563848-0.html attachment-2581134-0.html

Description george 2025-05-06 22:38:24 UTC

SUMMARY
***
As in the summary above, the 2 head system with differing resolutions causes (sometimes) the image to appear off center and/or to spill onto the second head. A system update often causes this. Setting the 2 heads to the same resolution (sometimes) fixes this, even when the resolution is changed back.
It would appear the the image position code is mixing location information from the 2 heads rather than working with the one head it is trying to put the image on.

STEPS TO REPRODUCE
1. 2 head system configured side by side. Differing resolutions
2. Choose a "Picture of the Day" for each head.
3.

OBSERVED RESULT
One or both images appear off center and/or part of image is on the wrong head.
Setting the resolutions the same usually gives the correct display.
When switching back the image on the lesser resolution screen may be off center with a portion cutoff. Clicking mouse 1 on that screen the pops up the rest of the image on the screen of higher resolution.

Note: I have also had cases where the image from the higher resolution screen spilled on to the lesser head, I am not sure how to reproduce this result.

EXPECTED RESULT
Each head should have its own image centered and not spilling on to the other head.

SOFTWARE/OS VERSIONS
Windows:
macOS:
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: Operating System: Fedora Linux 42
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.9.0

ADDITIONAL INFORMATION

Comment 1 Nate Graham 2025-05-07 15:06:02 UTC

Are you using the term "2 head" to mean "two screens are connected", or are you actually using the formal multi-head support? If you don't know what that means, the answer is no. :)

Comment 2 george 2025-05-07 18:20:52 UTC

Created attachment 181036 [details]
attachment-2507129-0.html

Two screens NOT the formal multi-head.

Comment 3 Nate Graham 2025-05-07 18:50:57 UTC

Thanks.

Are you using the X11 session, by any chance? If you don't know, the answer is no.

Does the issue happen when using a static wallpaper on each screen, and not a picture of the day wallpaper?

Does it happen for *all* picture of the day wallpaper types?

Comment 4 george 2025-05-07 20:24:17 UTC

Created attachment 181044 [details]
attachment-2550870-0.html

It is X11 (I am finding Wayland a bit dicey).
Seems to happen or all wallpaper types.

Comment 5 Nate Graham 2025-05-07 20:30:52 UTC

In that case this is probably expected, as the Plasma X11 session doesn't offer good support for mixed-DPI multi-monitor arrangements.

Can you check on Wayland to see if it works?

Also, how did you get an X11 session on Fedora? They don't include it nowadays. Did you get it via some 3rd-party repo or manual action?

Comment 6 george 2025-05-07 20:56:14 UTC

Created attachment 181046 [details]
attachment-2563848-0.html

So sorry, my login screen only offers plasma(X11)
Not sure how it came to be the only selection.  FYI I have been updating 
via Discover since Fedora 37 or 38.
In any case Wayland, at least back then, did not seem to play well with 
tcl/tk, so I moved away from it.
I will look into adding it as a login option.

Comment 7 george 2025-05-07 21:36:18 UTC

Created attachment 181048 [details]
attachment-2581134-0.html

Well, after a bit of searching, I was being restricted to X11 by sddm.config
As to the bug, it is not present in Wayland.

Comment 8 Nate Graham 2025-05-08 14:23:32 UTC

Thanks. At this point the bug is semi-known and not easily fixable in the Plasma X11 session due to its poorer handling of mixed-DPI multi-monitor systems. I would *strongly* encourage a move to the Wayland session to make this hardware setup work properly.