User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:65.0) Gecko/20100101 Firefox/65.0

Steps to reproduce:

Fedora 29 x86_64 X-Server (Cinnamon)
Download Firefox 66 tar.bz from Mozilla
Create a new profile.
Visit : http://trirand.azurewebsites.net/grid/functionalitycontextmenu
Right click in grid

Actual results:

context menu appears, but immediately disappears when the right mouse button is realsed

Expected results:

menu should continue to be displayed until choice is selected.

Works in (Linux) all versions <=65
Works in (Windows 7) all versions 66,<66 67b4)
Works in Chromium (Linux) Fedora 29 x86_64
Works in Chrome (Linux) Fedora 29 x86_64
Works in Chrome (Windows 7 x86_64) All versions 73 <73

Hi.

I have this issue.

Have you tried to maximize the window before trying to reproduce. Does it still happen?

Could you also try the following:

1- Make a new profile
2- Go to about:config and set the following options to false:
extensions.pocket.enabled
identity.fxaccounts.enabled
3- restart the browser and try to click on an empty part of a page.

Does it highlight all the content (select all) of the page?

More info on this issue:

https://bugzilla.mozilla.org/show_bug.cgi?id=1539712

Having the same issue since upgrading to 66.0.2 (64-bit). Someone came into my office said our context menus were not working, I tried and they were fine. But then Firefox updated to this version and I tried again and saw this same error.

Any update, this is having an impact on my clients. Chrome is now the workaround.

Regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=f6eebcc14c22762f521fb567a9588963b8720592&tochange=61570c16c2d564c24fab36713fb169c4144453e9

Regressed by:
61570c16c2d5 Olli Pettay — Bug 1512259 - No need to special case <button> in marionette, r=ato
eb4344bead3e Olli Pettay — Bug 1511388, ensure datetime reset button is the target for the click, r=timdream
7029e8b4d7d0 Olli Pettay — Bug 1498383 - clear.py relies on old Gecko's <button> hit testing, r=ato
36b949bef798 Olli Pettay — Bug 1089326, make <button> hit testing similar to other elements which may have some content, and for click target find the common (interactive) ancestor, r=masayuki