Bug 468315

Summary: Display Configuration incorrectly reads X11 as Wayland and blocks unsupported (fake) display resolutions
Product: [Plasma] kwin Reporter: kdebugz
Component: platform-x11-standaloneAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: minor CC: 0456523, nate
Priority: NOR    
Version First Reported In: 5.27.4   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: https://invent.kde.org/plasma/kscreen/commit/785148788d4841b5dc8c54293dc7e347a568299f Version Fixed/Implemented In: 6.0
Sentry Crash Report:

Description kdebugz 2023-04-09 04:59:37 UTC 
SUMMARY
Display Configuration does not support weird resolutions on a non-standard secondary display in X11 and claims it is in Wayland.

STEPS TO REPRODUCE
1. Launch X11 Plasma session with an unusual secondary display (e.g. an 800x1280 display masquerading as 1080x1920) over HDMI
2. `echo $XDG_SESSION_TYPE`: should return `x11`
3. Navigate to Display Configuration

OBSERVED RESULT
Note that Resolution is fixed at one value (no dropdown) with the note: "Using unsupported resolutions was possible in the Plasma X11 session, but they were never guaranteed to work and are not available in this Plasma Wayland session." even though the current session is X11, not Wayland.

EXPECTED RESULT
Multiple resolution options available even though they may not be supported by the display natively. Absence of a warning that "unsupported resolutions are not supported in Wayland" in an X11 session.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 5.27.4
KDE Frameworks Version: 5.104.0
Qt Version: 5.15.8
Kernel Version: 6.2.10-arch1-1 (64-bit)
Graphics Platform: X11
Processors: Intel® Core™ i5-8250U

ADDITIONAL INFORMATION
Linked KWin issue: https://invent.kde.org/plasma/kwin/-/issues/144
Similar issue reported (not shared on bugs.kde.org): https://www.reddit.com/r/openSUSE/comments/u68bo3/154_plasma_fixed_at_low_res_thinks_im_on_wayland/
Comment 1 kdebugz 2023-04-09 07:51:10 UTC 
This particular monitor seems to be so defective that it doesn't work in any mode on half the devices I've tested it on, so maybe ignore this bug.
Comment 2 Bug Janitor Service 2023-04-09 10:35:20 UTC 
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kscreen/-/merge_requests/202
Comment 3 Zamundaaa 2023-04-09 16:05:14 UTC 
Git commit 785148788d4841b5dc8c54293dc7e347a568299f by Xaver Hugl.
Committed on 09/04/2023 at 16:03.
Pushed by zamundaaa into branch 'master'.

kcm: remove text about unsupported modes on Wayland

It's not true anymore and can confuse the user, as it can also be shown
on X11

M  +1    -1    kcm/package/contents/ui/OutputPanel.qml

https://invent.kde.org/plasma/kscreen/commit/785148788d4841b5dc8c54293dc7e347a568299f
Comment 4 Nate Graham 2023-08-02 20:58:40 UTC 
*** Bug 472877 has been marked as a duplicate of this bug. ***