1955000 - The Firefox Sidebar and Tab strip are not painted if Firefox is started while High Contrast is enabled on Windows

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[Rares Doghi, Desktop QA]

Attachment: HCSIDEBAR.mp4

Found in

• Nightly 138.0a1 (2025-03-19)

Affected versions

• Nightly 138.0a1 (2025-03-19)
  Beta 137.0b7
  Release 136.0.2
  ESR 128.8.0esr

Affected platforms

• Windows

Preconditions
Enable High Contrast
Enable the Firefox Sidebar.

Steps to reproduce

1. Launch Firefox While High contrast is enabled on Windows.

Expected result

• The Firefox Sidebar and Tabstrip should be painted.

Actual result

• The Firefox Sidebar and Tab strip are displayed with the light theme.
  If we move the Sidebar to a different position it will repaint.

Please not that in older builds like Release or ESR this issue only occurs the first time the user starts Firefox while High contrast is enabled.

Regression range
Not a Regression

Comment 1

[Morgan Reschenberg [:morgan]]

Marking a11y-S2 because enabling HCM and then starting Firefox is the default workflow for many users, and defaulting to light mode here carries a photosensitivity risk

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:jswinarton, could you have a look please?

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