Closed Bug 1560499 Opened 2 years ago Closed 2 years ago

about:addons preferences page text is blurry


(Core :: Graphics: WebRender, defect, P3)

69 Branch



Tracking Status
firefox-esr60 --- unaffected
firefox67 --- unaffected
firefox67.0.1 --- unaffected
firefox68 --- unaffected
firefox69 --- verified


(Reporter: ke5trel, Assigned: gw)


(Regression, )


(Keywords: correctness, regression)


(2 files)


  1. Make sure gfx.webrender.all = true (Ubuntu 19.04).
  2. Install Decentraleyes extension.
  3. Go to about:addons, click on Decentraleyes and open its Preferences tab.

The text in the preferences page is blurry and too bold. Most extensions appear to be affected, Decentraleyes is more noticeable than some others.

Regression window:

Regressed by Bug 1558106.

Confirmed bug & regression range on Ubuntu 19.04 / GTX1060.

Has Regression Range: --- → yes
Has STR: --- → yes
Flags: needinfo?(gwatson)
Keywords: correctness
OS: Unspecified → Linux
Hardware: Unspecified → x86_64

(Offtopic/observation: There seems to be another bug: If I detach this about:addons tab to create a new window, the "Preferences" section becomes empty.)

Also confirmed with Win10/GTX1060. I haven't noticed it elsewhere yet.
good: mozregression --repo autoland --launch 855d557b82a20e1ed87af46bceac3b918534d37e --pref gfx.webrender.all:true -a
bad: mozregression --repo autoland --launch 431c5142ff3ad102328d90cb29470b20ccd1271e --pref gfx.webrender.all:true -a

OS: Linux → All
Priority: -- → P3
Hardware: x86_64 → All
Assignee: nobody → gwatson
Flags: needinfo?(gwatson)

I can reproduce the issue. On non-WR, the subpixel AA rendering gets disabled on the preferences tab panel, due to it having a transparent background.

However, WR is not correctly detecting the case of a transparent background, so it keeps subpixel AA enabled, which gives incorrect blend results.

Some pages from Gecko produce a display list for the main content
tile cache that has a transparent background. Detect these cases
and disable subpixel text rendering to ensure correct blending.

(In reply to Jan Andre Ikenmeyer [:darkspirit] from comment #2)

(Offtopic/observation: There seems to be another bug: If I detach this about:addons tab to create a new window, the "Preferences" section becomes empty.)

Filed as Bug 1560835.

Pushed by
Fix subpixel detection for transparent tile caches. r=kvark
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla69

Checked on Unbuntu 18.04.2 LTS FF Nightly 69.0a1 with Build ID: 20190619214046) from before the fix and reproduce the issue there.
Unfortunately we did not have Ubuntu version 19.04 and only managed to verify the fix in Unbuntu 18.04.2 LTS 64- Bit and on Win - 64 Bit on Nightly Fx Nightly 70.0a1 (20190711230342) and Beta 69.0b3 (20190708182549).
Release version Ff 68 was unaffected.

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