[afonsojramos]

Summary

With the Glass theme on macOS, hovering a notification row shows its action buttons on a near-white box with a hairline border, separate from the row. Windows has the same problem. #3604 fixed it only on Linux.

The rail used the macOS tooltip material: a near-opaque fill with a backdrop blur. #3604 replaced that fill on Linux with the app background under the row's hover wash, which works because the Linux window is opaque. On macOS the window background is the native vibrancy material, which CSS cannot paint, so any fill there reads as a slab.

Under Glass, the rail now has no fill on any platform. The hovered row's own surface shows through, so the rail reads as part of the row. To keep row content from showing through the buttons, the rail's siblings are clipped at the rail's leading edge while the rail is shown:

• The row or header (.group) becomes an inline-size container, so 100cqw locates the rail inside each sibling's box.
• The clip inset follows the rendered button count (0 to 3 small IconButtons, 1.75rem each), because disabled actions render nothing. Read rows show one button, and read Gitea, GitLab and Bitbucket rows show none.
• The clip extends past the other three edges so focus rings are not cut off.

This replaces both the frosted rule and the Linux-only rule. Classic is unchanged, and Reduce Transparency and Increase Contrast still fall back to solid surfaces.

Testing

• vp check and the renderer test suite pass.
• Checked on macOS in Glass: the rail blends into hovered notification rows and headers.
• Rendered in Chromium with a simulated vibrancy background and with the opaque window, in light and dark, for notification rows, repository and account headers, and keyboard focus. Long titles stop at the rail, and tooltips inside a hovered row still render outside it.
• New visual-suite assertions check that the Glass rail has no fill and that row content is hit-testable up to the rail's leading edge but not inside it, for 3-, 1- and 0-button rails. They fail against the previous CSS.
• The Glass screenshot baselines are not regenerated: they are arm64 renders, which this change could not reproduce locally. If the Visual Regression job flags them, they need updating from its output.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[setchy]

Any way our visual regression suite could catch this in future?

[setchy]

the notification action hover color looks similar to the glass mode tooltips for sidebar buttons (ie: Settings, Filters)

[afonsojramos]

the notification action hover color looks similar to the glass mode tooltips for sidebar buttons (ie: Settings, Filters)

yeah, but one's behaviour is clearly floating on top of other things, where the other is action buttons within the row. HOWEVER, one could change them instead to three individual buttons. But maybe that can be a later experiment.