I remote in to my work PC, and I run Zoom in the same AppVM, so that I can talk to my colleagues and share my screen with them. Screensharing works - they can see my remote machine’s screen - but I cannot stop screensharing without killing the zoom process. There is a “Stop screensharing” button but clicking it never does anything. I don’t have this problem on other operating systems, or on Linux except on Qubes.
I have full-screen permission enabled for this AppVM so that the remote-desktop application (Citrix) can take over the screen. Again, screen-sharing seems to work fine with this - it’s just stopping screen-sharing that’s a problem.
Qubes does pop up a warning about a large overlay window when I start screen sharing from Zoom. I always just dismiss this warning.
Are you running the Zoom client or are you using Zoom from within a browser?
I don’t know what the Zoom client does, but when running it inside Chrome/Brave it should use the same standard way of screen sharing that WebEx and Teams use too. I’m not an expert in this topic, but my impression is that this is somewhat standardized.
If you are not using the browser based version, maybe give it a try. I like it better because that way Zoom/WebEx/Teams are forced to use the interfaces the browser gives them and somewhat limited in what else they can do. Not a big concern, since all this stuff is inside a qube anyway but still …
I found a solution using the official Zoom client. First exit full screen mode in Citrix, then hover over the black bar which doesn’t seem to be clickable. This will expand the Zoom controls. Then click on “Pause screen share”. (If you don’t see this button, you might need to upgrade your Zoom.) Then collapse the Zoom controls. This seems to remove what I refer to as an “invisible screen capture overlay window”. Then you should be able to click on the “Stop screen share” button.