Affected versions

• 85.0b8
• 86.0a1 (2021-01-12)

Affected platforms

• Windows 10
• Windows 7
• macOS 10.15
• Ubuntu 20.04

Steps to reproduce

1. Make sure print.tab_modal.enabled is set to true in about:config
2. Open Print modal on any long page
3. Scroll the Preview a little bit and observe that the paginator reflects correctly the page numerotation
4. Resize the window
5. Hover the preview and observe the paginator value

Expected result

• The paginator updates its value in accordance with the resize action

Actual result

• The paginator value remains the one shown before the resize action

Regression range

• Not a regression, behavior present since paginator implementation

Additional notes

• Paginator updates its value post resize at soon as the preview is scrolled again

We might need to listen for resize events in addition to scroll events to catch this

The resize listener would go in PrintingChild.jsm [1], it should be able to reuse the scroll handler [2].

[1] https://searchfox.org/mozilla-central/rev/a9851cca236e03d088d7528dd27445080475a68e/toolkit/actors/PrintingChild.jsm#41
[2] https://searchfox.org/mozilla-central/rev/a9851cca236e03d088d7528dd27445080475a68e/toolkit/actors/PrintingChild.jsm#103