Alt-Tabbing out of Firefox is broken in 3.32
Since upgrading to GNOME Shell 3.32, I've noticed that after a few minutes, Firefox gets stuck in a weird state where it always appears last in the application switcher (alt-tab). In addition menus (e.g., hamburger button or right-clicking on a web page) don't appear.
Restarting Firefox fixes things for a while but soon it get stuck in this state again. GNOME Shell otherwise seems to operate normally with one exception: I have Super+Enter bound to launching gnome-terminal; when I do so, terminal windows appear in the background (and I get a 'Terminal is ready' notification).
This is with Firefox 65 and 66, and didn't happen with GNOME Shell 3.30. This may well be a Firefox problem, but since it only appeared after upgrading GNOME Shell, I thought I'd start here, since I need some suggestions for things to check before filing a bug with Firefox.