Lock screen rendering scaled/squished

[nhaggin]

Distribution

Mint 21.2 x86_64

Package version

5.8.1

Graphics hardware in use

AMD Radeon RX 6650XT

Frequency

Always

Bug description

When using fractional scaling with dual 4K monitors, the lock screen renders only on the primary monitor, scaled horizontally to about 3/4 of the screen width but correctly scaled vertically.

This seems to happen only with fractional scaling; if I scale the desktop to either 100% or 200%, the lock screen renders correctly across both monitors.

Steps to reproduce

Lock the screen/start the screensaver

Expected behavior

Lock screen should render across 100% of both monitors at desktop scaling

Additional information

~/.xsession-errors contains the following after locking:

** (cinnamon:4792): WARNING **: 10:47:34.417: Skipping layers 1..n of your pipeline since the first layer is sliced. We don't currently support any multi-texturing with sliced textures but assume layer 0 is the most important to keep

cinnamon-screensaver --debug --hold doesn't seem to show anything of interest:

$ cinnamon-screensaver --debug --hold
Fractional scaling active: True
Trying to connect to logind...
Starting screensaver...
Debug mode active
Cinnamon Screensaver support not found in current theme - adding some...
service: 'GetActive' received, poking application.
org.gnome.ScreenSaver is gone from the session bus
org.mate.ScreenSaver is gone from the session bus
service: 'GetActive' received, poking application.
login client: found session path for user 'nhaggin' (session_id: c2): /org/freedesktop/login1/session/c2
Successfully using logind

[rimeraz]

This sounds similar to #337, doesn't it?

[nhaggin]

Might be, though in my case double (200%) scaling works just fine. Thanks for the suggestion to use gnome-screenshot with the delay option, BTW, because now I have an example screenshot of my own:

[nhaggin]

I really don't want to be That Guy, but it would be nice to at least see an acknowledgement of some kind, even "won't fix."

[nhaggin]

Can confirm issue is still present on 6.0.2 (21.3/Virginia).

[mtwebster]

Sorry, acknowledged.. there have been a number of issues related to fractional scaling, due to changes in Cinnamon a few releases ago that still manifest in certain situations and with certain graphics hardware.

[nhaggin]

@mtwebster thank you. I regret that I have no time at the moment to poke at the code myself.

[gregzme17]

This is very similar to linuxmint/cinnamon#10998
It is still happening. @mtwebster , can I provide any logs or anything to help you?

Radeon 6600XT
3 monitors running 1440p resolution
Mint 21.3
Cinnamon 6.0.4