Transparent/flickering borders with scaling enabled

[erahhal]

Hyprland version

Hyprland 0.48.1 built from branch v0.48.1-b at commit 29e2e59 (version: bump to v0.48.1).
Date: 2025-03-28
Tag: v0.48.1, commits: 29e2e59
built against:
aquamarine 0.8.0
hyprlang 0.6.0
hyprutils 0.6.0
hyprcursor 0.1.12
hyprgraphics 0.1.3

no flags were set

Regression

Yes, but for several versions. Not sure when it broke, been at least half a year.

Describe the bug

• On the latest version (0.48.1). Been seeing this for at least half a year on previous versions as well.
• Happens with any toolkit (gtk, qt, or otherwise)
• Happens with both wayland and xwayland
• Happens with both floating and tiled windows
• Happens with electron and non-electron apps
• Happens between waybar and tiled windows, and group bar and tiled windows
• forcergbx has no effect
• All gaps and borders turned off, it still happens
• Shadows and blur on and off have no effect
• Sometimes flickers randomly
• Sometimes only happens on one or two sides of the window

GOES AWAY with scaling off. Gets better or worse depending on the scaling value. For instance, the worst is a 5k 5120x2160 monitor at 1.333333 scaling. Setting it to 1.25 scaling is far better, but still happens with some floating windows. 1.25 is a factor of both 5120 and 2160 so not sure what the problem is.

Also happens within windows: this the chrome tab bar (running wayland):

Reproduction steps

Set scaling as described above

System info and config

systeminfo.log

[erahhal]

This gets rid of the problem for some reason, but not sure what the downside is:

windowrulev2=opacity 0.999 0.999, class:^(.*)$

[yvvki]

Another workaround is by setting cursor.zoom_factor to 0.99999. But yeah, these will create overheads.

[vaxerski]

thats a way worse workaround

[erahhal]

Well, it gets rid of the problem for everything except for the tab bar border in chrome, the last image above. In any case the window rule above is clearly masking the issue rather than resolving it.

[ctilley83]

I have a similar issue with Quickshell and Caelestia dots. The bar does not anchor to the screen extents leaving a 1px gap around the entire screen. Of course it only happens with my desired scaling of 1.25. All other allowed scaling values work fine. Are we sure 1.25 is a precise value or is there rounding happening here?