[Affected versions]:

• Firefox 68.0a1 (20190408193006)
• Firefox 67.0b9(20190408123043)

[Affected platforms]:

• Win 7 64-bit
• Ubuntu 14.04.LTS 32-bit

[Prerequisites]

• Set the preference extensions.htmlaboutaddons.enabled to true and restart the browser

[Steps to reproduce]:
1.Install an extension from about:addons.
2.Select Extensions from about:addons.
3.In Manage Your Extensions, hover over the more options menu button.
4.Click on it.

[Expected results]:

• The the drop-down menu opens.

[Actual results]:

• After clicking once, the drop-down menu is not opening, only on the second click.

[Notes]

• When you click the second time, if you use the right-click button, the drop-down menu and the context menu opens at the same time, hiding the drop-down menu, under the context menu.

• This issue is not reproducing on Mac OS X 10.14.1.

Please see the attached video.

There was a bug where the panel would be hidden on the first click on Windows (and I think Linux, too). This was happening because the focusin event would trigger after mousedown and hide the panel on the first click. Then the button would have focus and we wouldn't get a focusin on the second click.

This updates the focusin handler to check if this is the first focusin event, and ignore it if the event target matches our triggering event's target.

https://hg.mozilla.org/mozilla-central/rev/92e638c435da

Behind a pref, disabled for 67.

This issue is verified as fixed on Firefox 68.0a1 (20190501215533) under Win 7 64-bit and Ubuntu 14.04.LTS 32-bit.

Please see the attached video.