Wallpaper Spanning Across Dual Monitors Not Working in Cinnamon

Distribution

Linux Mint 22 Cinnamon

Package version

6.2.9

Graphics hardware in use

Intel Corporation HD Graphics 530

Frequency

Always

Bug description

I’m experiencing an issue where a wallpaper is not spanning properly across my dual monitors. Instead of stretching the wallpaper across both screens, the image appears centered, leaving blank space on both monitors.

Steps to reproduce

Use Linux Mint 22 with Cinnamon.
Connect two 1080p monitors side-by-side (combined resolution: 3840x1080).
Set a 3840x1080 wallpaper in the Cinnamon background settings and choose the "spanned" option.
The wallpaper does not span across both monitors as expected.

Expected behavior

Expected Result: The wallpaper should span evenly across both monitors.

Actual Result: The wallpaper appears centered between the two monitors, leaving blank spaces on both sides.

Additional information

Output of xrandr:

Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
HDMI-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm
1920x1080 60.00*+ 50.00 59.94
1920x1080i 60.00 50.00 59.94
1680x1050 59.88
1280x1024 75.02 60.02
1440x900 59.90
1280x960 60.00
1280x800 59.91
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-3 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 598mm x 336mm
1920x1080 60.00*+ 50.00 59.94
1920x1080i 60.00 50.00 59.94
1680x1050 59.88
1280x1024 75.02 60.02
1440x900 59.90
1280x960 60.00
1280x800 59.91
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DP-3 disconnected (normal left inverted right x axis y axis)

Reproduce the issue from Cinnamon background settings with two side-by-side 1920x1080 monitors and the provided xrandr layout. Start by tracing the background wallpaper spanning path; done means a 3840x1080 image spans both monitors without blank side areas and the behavior is covered by an appropriate regression check.