Main Toolbar of Firefox is missing after minimize/ restore, when Firefox tiled without title bar

Distribution

Linux Mint 22.1 Cinnamon

Package version

6.4.8

Graphics hardware in use

No response

Frequency

Always

Bug description

Main Toolbar (tab-bar) of Firefox is missing after minimize/ restore, when the Firefox Window (without title bar) is tiled.

Steps to reproduce

• Open Firefox
• Configure Firefox to not show the "Title bar"
  • right click on the Toolbar, choose "Customize Toolbar", unselct "Title bar"
• Grap the Toolbar of firefox and draw it to one of the borders to snap / tile (i.e. Firefox for half of the screen)
• In Cinnamon Toolbar, click on the Firefox icon twice, to minimize / restore Firefox
• result: The main Toolbar of Firefox is not visible.

Expected behavior

Minimize / restore of the Firefox window should not have an effect on the Main Toolbar of Firefox.

Additional information

This issue appeared first some days ago - and can be consistently reproduced on my computer.
I use snap / tiling frequently.

This issue does not appear, when the Firefox Window is not snapped/ tiled.
This issue does not appear, when the Title Bar of Firefox is shown.

Workaround:
If the Toolbar is missing after "Restore", it is sufficient to "Unmaximize" the Firefox Window to get the Main Toolbar back.

Start by reproducing the minimize/restore sequence on Linux Mint Cinnamon with Firefox tiled without its title bar, then inspect muffin's handling of tiled windows during minimize and restore. Done means the Firefox main toolbar remains visible after restore, while existing behavior for untiled windows and windows with title bars remains unchanged.