[Bug] Background images are not fully rendered when the tollbar menu hides.

[jomisica]

Steps to reproduce

Navigate to https://www.sleeping.pt/wp/2020/08/22/test-parallax-cover/

Watch the following video that shows the problem.
https://www.sleeping.pt/wp/wp-content/uploads/2020/10/2020_10_30_21_58_13-2.webm

Expected behavior

Whenever the toolbar disappears, redraw the background image.

Actual behavior

The background image is not redrawn.

Device information

• Android device: Galaxy A20e
• Fenix version: 82.1.1

┆Issue is synchronized with this Jira Task

[winofi]

Ran into the same issue. Minimal example can be found here: https://fggs.de/asdf.html
The issue seems to be that the fixed background image size does not take the toolbar size into account.
Result:

Tested on same version on Xcover 4s

[LaurentiuApahideanSV]

I can confirm the issue is reproducible Firefox Preview Nighlty 201105 (Build #2015773803).

Devices used:

• Samsung Galaxy S9 (Android 8.0.0)
• OnePlus 6T (Android 9)

[Mugurell]

This seems like a GV issue, moving to Bugzilla.

[Mugurell]

Moved to bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1690302

Change performed by the Move to Bugzilla add-on.