Affected versions

• 85.0b7
• 86.0a1 (2021-01-11)

Affected platforms

• Windows 10
• Windows 7
• Ubuntu 20.04
• macOS 10.14

Steps to reproduce

1. Make sure print.tab_modal.enabled is set to true in about:config
2. Open https://www.qq.com/?fromdefault
3. Hit CTRL + P
4. Click inside the scale field
5. Hover the preview in order for the paginator to be displayed
6. With the paginator in focus, change the scale values several times

Expected result

• The page number transition is smooth, no flicker is triggered

Actual result

• The paginator flickers

Regression range

• Not a regression, visible since the paginator was implemented

Additional notes

• The flicker intensity is inconsistent on random webpage or on the same page and occurs regardless of the destination