Strange highlights in dark GTK3 themes

[01micko]

Expected Behavior

Open thunar file manager with a Yaru dark theme (any one) and get a clean background in the in the main scrolled window and a second unfocused window.

Actual Behavior

Focused window is ok but strange highlights appear around the text in the main scrolled window of the unfocused window. It happens whenever a thunar window hasn't got focus, ie I can have four thunar windows open and a browser and if the browser has focus all 4 thunar windows show the issue.

Steps to Reproduce the Problem

Apparently this is a wayland issue so you must be running labwc or sway wlroots compositors.

1. Open Thunar
2. From the menu bar click "View"
3. Check "Show File Highlight"
4. You see the darkened highlights under each icon in unfocused thunar

Software that presents the issue

• Name: Thunar
• Version: 4.18.11
• OS version: Debian GNU/Linux trixie/sid - running labwc wayland compositor. Also occurs in sway.

Yaru version

24.10.4-0ubuntu1-1-gcd727585c

Screenshots

Upstream check

The bug also appears upstream - although a little more faint.

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I tried to fix it but the best I came up with was a css workaround in $HOME/.config/gtk-3.0/gtk.css

.thunar .view:selected { background-color: @theme_selected_bg_color; }
.thunar .view { background-color: alpha(@theme_bg_color, 0.8); }

I used GTK Inspector to come up with this by trial and error. It isn't a fix but does a decent job of working around the issue. It becomes barely noticeable.