User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

Focus the address bar, then click-drag downwards on the new tab "+" button.
This started happening with since the new feature where the address bar gets magnified and outlined blue when focused.

Actual results:

The menu doesn't open.

Expected results:

The menu should open, and a container should be able to be selected by releasing the mouse button while hovering an option.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

I can reproduce this on 78 but not 79 or 80. Could you please try with Beta or Nightly and let us know whether it happens there?

Actually, the menu appears for me on 78 once I set the privacy.userContext.enabled pref. Are you sure you've set it?

(In reply to Drew Willcoxon :adw from comment #2)

I can reproduce this on 78 but not 79 or 80. Could you please try with Beta or Nightly and let us know whether it happens there?

I can confirm that it doesn't work in Nightly.

(In reply to Drew Willcoxon :adw from comment #3)

Actually, the menu appears for me on 78 once I set the privacy.userContext.enabled pref. Are you sure you've set it?

This was already set to True for me, still no menu.

I'd like to stress that this ONLY happens when click+dragging downwards from the "+" button when the address bar is focused. Right clicking it still works fine.

Are you waiting a moment after clicking and before starting to drag downward? I'm not sure why I can't reproduce it. Are there any errors in the browser console? Could you please try to reproduce it in safe mode and a new profile:

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

(In reply to Drew Willcoxon :adw from comment #5)

Are you waiting a moment after clicking and before starting to drag downward? I'm not sure why I can't reproduce it. Are there any errors in the browser console? Could you please try to reproduce it in safe mode and a new profile:

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

Not waiting, it should happen immediately upon dragging. It only seems to break if the "+" button happens to take up the same horizontal space as the address bar. If it's either to the left or the right of the horizontal space that the address bar occupies it still works fine.

All right, thanks for the video. I do see the difference, but I imagine that if you pause a moment before dragging, the menu will open. At least it works for me. For completeness I'll also note that you can right-click to open the menu. I don't mention these things to invalidate your report.