Open Bug 1535583 Opened 4 years ago Updated 8 months ago

[Youtube] Unsubscribed channel popup changes slightly its size on tab navigation


(Core :: Layout: Text and Fonts, defect, P3)




Tracking Status
firefox66 --- wontfix
firefox67 --- fix-optional
firefox68 --- fix-optional


(Reporter: asoncutean, Unassigned)


(Keywords: regression)


(1 file)

Attached image screencast issue.gif

[Affected versions]:

  • 66.0 (20190314174725)
  • 67.0a1 (2019-03-14)

[Affected platforms]:

  • Windows 10 x64
  • Windows 7 x64
  • Ubuntu 16 x32
  • macOS 10.13

[Steps to reproduce]:


  • Make sure to previously subscribed to a youtube channel
  1. Go to and login
  2. Click the “Subscribed” button
  3. Navigate with the Tab key inside the Unsubscribed popup

[Expected result]:

  • No popup size modification is triggered by the Tab navigation action.

[Actual result]:

  • The popup size slightly increases.

[Regression range]:

  • This issue looks like an old regression, reproducible way back to Fx 47.0a1, but not on Fx 31.0a1. I will provide more information asap.

[Additional Notes]:

  • Issue not reproducible with Chrome or Internet Explorer.

Disabled HWA fixes the issue on Nightly67.0a1 Windows10.
It seems difference of width of boldly(synthesized?) font rendering between browsers/text rendering engine.

Component: Layout → Graphics: Text
Component: Graphics: Text → Layout: Text and Fonts
Priority: -- → P3
Severity: minor → S4
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