70853n/272840 add hover colors

[70853n]

Proposed changes

Fixes #272840 by introducing two theme color variables.

Testing

Automated tests

Automated test already exist under /vscode/src/vs/workbench/contrib/themes/test/node/colorRegistry.releaseTest.ts

Manual testing

Steps to reproduce

1. Run a dev instance of VS Code
2. Go to Preferences: Open User Settings (JSON)
3. Add the following:

  "workbench.colorCustomizations": {
    "titleBar.activeHoverBackground": "#000000",
    "titleBar.activeHoverForeground": "#ffffff",
    }

4. Hover over the Back and Forward buttons in the title bar

Expected behaviour

Unless a button is disabled it should show white text on a black background.

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@bpasero

Matched files:

• src/vs/workbench/browser/parts/titlebar/media/titlebarpart.css
• src/vs/workbench/common/theme.ts

[70853n]

@microsoft-github-policy-service agree

[Copilot]

Pull request overview

This PR adds hover color customization for title bar actions (back/forward navigation buttons and command center) by introducing two new theme color variables: titleBar.activeHoverBackground and titleBar.activeHoverForeground. The implementation follows existing VS Code theming patterns and integrates with the color registry validation tests.

Key Changes

• Added two new theme color definitions following the existing hover state pattern
• Configured initial color values for dark and light themes
• Applied the colors in CSS to title bar action hover states

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/vs/workbench/common/theme.ts	Registered two new theme colors using toolbarHoverBackground and TITLE_BAR_ACTIVE_FOREGROUND as defaults, consistent with menubar selection pattern
src/vs/workbench/services/themes/common/workbenchThemeService.ts	Added initial color values for both dark and light themes following the existing color scheme
src/vs/workbench/browser/parts/titlebar/media/titlebarpart.css	Applied hover styles to title bar action labels, though contains duplicate rule that should be removed
build/lib/stylelint/vscode-known-variables.json	Added CSS variable names in correct alphabetical order for stylelint validation