User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:82.0) Gecko/20100101 Firefox/82.0

Steps to reproduce:

Firefox 82.0.3 running on MacOS 11.0.1 (Big Sur)

In Firefox full screen mode, I move my cursor to top of window and drop down appears.

Actual results:

Drop down appears white and blank (actual menu items above it) . Frozen. Can't access tabs or the ability to return screen to normal view

Expected results:

Menu items should be the dropdown, and it doesn't retract when I move cursor away from it. It seems only way to resolve issue to shut Firefox down and restart.

Hi Barry,

I wasn't able to reproduce this issue on MacOS Big Sur 11.0.1 using Firefox 83.0 or Firefox Nightly 85.0a1

Could you check If the issue also occurs to you in safe mode?
You can find out how to do this here:
https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode#w_how-to-start-firefox-in-safe-mode

If it still does, try making a new profile and check again (you won't lose your old one)
Here is a link that can help you do that:
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed

Also, make sure to have the latest version of BigSur

Thank you!

Hi, Peter -

Thanks for this.
I've since discovered that the dropdown only freezes when there is more than one tab open.

Following your guidance, I went into Safe Mode. The freezing did not seem to be an issue there with multiple tabs open, the bar would slip up out of the way as expected when I moved the cursor away. So it looks like extensions or hardware acceleration.

Went back in regular mode and disabled all add-ons. Restarted Firefox. Went to full screen mode - no problem with more than one tab open.
Back into Add-ons - chose one to enable. Restarted - same process - only this time the bar froze. Hmm. Could that add-on be the issue? Disabled it, enabled a different one, restarted, and...bar froze. Same process tried with others, same result.

Begins to look like any add-on is causing issue.

A bit of moot point if hardware acceleration on / off. Same results with / without add-on enabled.

Its beginning to look like a squiffy install of something to do with add-ons here. Fear it may mean a full and complete uninstall of any Mozilla / Firefox file and try again...?

Currently running FF 83.0 on MacOS 11.0.1

other items reported with big sur https://mzl.la/335rA6y

Reproducible steps

1. Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:84.0) Gecko/20100101 Firefox/84.0
2. Open a new window
3. Optional - go full screen
4. Right click on any tab then move the cursor to the top of the screen to reveal the Mac menu drop-down

Actual behaviors

1. With step 3:
   - The Firefox menu drop-down appears white and blank
   - The Mac menu drop-down is above it
   - Other Firefox UI elements are behind the Firefox menu drop-down

2. Without step 3:
   - The Mac menu drop-down appears
   - Other Firefox UI elements are behind the Mac menu drop-down

Expected behaviors
Refer to Safari for the expected behaviors.

1. With step 3:
   - The Firefox menu is part of the Firefox UI and not in a separate white and blank drop-down
   - Other Firefox UI elements are not obscured

2. Without step 3:
   - The Mac menu drop-down appears
   - Other Firefox UI elements are not obscured

(In reply to Daniel from comment #4)

Reproducible steps

1. Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:84.0) Gecko/20100101 Firefox/84.0
2. Open a new window
3. Optional - go full screen
4. Right click on any tab then move the cursor to the top of the screen to reveal the Mac menu drop-down

Actual behaviors

1. With step 3:
   - The Firefox menu drop-down appears white and blank
   - The Mac menu drop-down is above it
   - Other Firefox UI elements are behind the Firefox menu drop-down

2. Without step 3:
   - The Mac menu drop-down appears
   - Other Firefox UI elements are behind the Mac menu drop-down

Expected behaviors
Refer to Safari for the expected behaviors.

1. With step 3:
   - The Firefox menu is part of the Firefox UI and not in a separate white and blank drop-down
   - Other Firefox UI elements are not obscured

2. Without step 3:
   - The Mac menu drop-down appears
   - Other Firefox UI elements are not obscured

These apply to https://bugzilla.mozilla.org/show_bug.cgi?id=1680869 too. Maybe they could be grouped into a single menu drop-down tracking bug.

In response to Daniel (above) - currently on Firefox 84.0.1 on Big Sur 11.1.

Re: Reproducible Steps - it would seem it's Step 4 that causes the freeze of the drop-down bar as I originally posted. If I open Firefox to full screen (Step 3), I can add additional tabs, and I can left-click them to choose them. If I move the cursor to top of screen, I get the white blank Firefox drop-down and the Mac menu drop-down above it (as noted in your Actual behaviours #1) - and this slides away as I move the cursor away.

If I right-click any tab, and then anytime afterwards move the cursor to top of screen to access Firefox / Mac drop-down (Step 4), both of these appear but then freeze - obscuring the Firefox toolbar - and not sliding away when cursor moved.

I am now able to regain control of Firefox with View > Exit Full Screen, but as name suggests, this takes app back to regular default, and the drop-down disappears.

Thanks for finding some clarification as to when the bug becomes active. Several versions of Firefox (and an OS update) later than original posting, and its still an issue. Pity. I miss the full functionality of earlier Firefoxes.

Closing this as duplicate of bug 738335, although there may be a new bug here with addons causing an actual freeze of the titlebar. In this case it might be worth filing a new bug under the extensions component.

Thanks Stephen - Posted also on bug 738335, now that you've brought that to my attention. This issue appears to be a duplicate of an older thread. Also with no resolution.