Steps to reproduce

1. Go to a website
2. Click on star icon to bookmark page (make sure Bookmarks Toolbar is selected as the destination)
3. Open new tab (Bookmarks Toolbar is hidden except on new tab)
4. Click on double chevrons to open additional bookmarks menu
5. Attempt to drag and drop the most recent bookmark to a different spot in the Bookmarks Toolbar

Expected behaviour
Bookmark should be moved to new spot.

Actual behaviour
Nothing happens, as the new bookmark can not be dragged into new spot. Instead, the cursor moves normally without dragging anything.

Notes
You may be successful on the first attempt, but the bug may manifest on subsequent attempts.

Reproduced on: Firefox 99.0.1 (64-bit) macOS Big Sur (11.6)

Tried multiple times with Fx 99.0.1 on a Big Sur mac and couldn't reproduce.

(Bookmarks Toolbar is hidden except on new tab)

You can change that to always show if you want: it's an option if you dig into "Toolbars" on the "View" menu

(In reply to Daniel Veditz [:dveditz] from comment #1)

You can change that to always show if you want: it's an option if you dig into "Toolbars" on the "View" menu

Yes I have this setting intentionally on. Thought it might potentially have something to do with the bug which is why I mentioned it. I did turn it off now and the bug stopped occurring on a new window. I restarted Firefox, turned it back on (i.e. selected "Only show on new tab") and the bug started happening again.

I have around 50 bookmarks in the bookmarks toolbar, which may or may not have something to do with it. I just reproduced it again now and in fact this happens with existing bookmarks not just new ones (if you try to drag any of them around within the double-chevron menu, nothing happens).

The severity field is not set for this bug.
:mak, could you have a look please?

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