Overview Description:
Clicking on one of the menus -- the hamburger menu, for example -- blocks keystrokes.

When a menu is open (the hamburger menu, or the + menu, for examples), my keystrokes don't work. The print screen key does not trigger a screenshot, my applications launcher shortcut does not trigger my applications launcher, and so on.

System Info:

• Pop!_OS 21.10 (based on Ubuntu 21.10)

Steps to Reproduce:

1. Install Celluloid via flatpak (in my case, I installed the flatpak via Pop!_Shop, Pop!_OS' app store);
2. Open Celluloid;
3. Click on a menu (the hamburger menu, for example);
4. Press a key that should do trigger an action system-wide (like the print screen key that should capture a photo of your screen);
5. Notice that the key is not working/not triggering the action it was supposed to.

Actual Results:
Keystrokes are blocked when menus are open.

Expected Results:
Keystrokes work when menus are open.

Version:
0.22

Additional Information:
Might be related: I've filed another bug report about black block/border behind/around menus: #729