Description of problem:

I am using the most recent versions of Gnome (Wayland) and Firefox on a three screen set-up and whenever I want to use a drop down menu on a web page, it does not correctly work -> it gets focus after clicking on it, but it never opens to let me select from the options. I know for sure that there are options on it.

In Firefox, the drop-down menu only works when the Firefox window is placed on the leftmost screen. I think that it does not have to be the leftmost, or the rightmost, but it probably is the one that registers first into the Wayland session. Drop-down menus work correctly on one screen setup (laptop screen). There is also no difference between a maximized and non-maximized window, drop-down works on one of the screens only.

Google Chrome works normally on any screen.

After switching to Xorg, Firefox behaves normally on all of the three screens.

Version-Release number of selected component (if applicable):

Firefox: 70.0.1-4
Gnome Shell: 3.34.1-4

How reproducible:

Always

Steps to Reproduce:
1. Run a setup with one primary and one secondary screen.
2. Navigate to https://docs.python.org/3/contents.html and try drop-downs in the upper-left corner.

Actual results:

They do not work except on one of the screens.

Expected results:

They should work everywhere.

Additional info:

Interestingly, on the Bootstrap page, https://getbootstrap.com/docs/4.3/components/dropdowns/, everything works as expected on each screen.