Screen recording, but only a single window

I want to make a short screen recording of a single window.

I’m on F31. I had the F27 version of “gtk-recordMyDesktop” floating around on the system, but that appears to assume Python 2 so it fell over and died. No surprise there; surely there is a modern replacement, right? You would think, but:

I have “fros” and “fros-gnome” installed, and while it let me select a window, clicking “record” resulted in:

2019-11-24 09:25:14,389 - abrt-screencast - ERROR - Failed to start GNOME screencasting: org.gtk.GDBus.UnmappedGError.Quark._g_2dio_2derror_2dquark.Code19: Invalid params

I’m not sure what that’s trying to tell me. Also, one of the buttons has a Python byte-string marker in it (the label is b'Select window', which makes me suspicious I’m going to find other bugs in this software).

I tried “simplescreenrecorder”, but when I tried to select a window it segfaulted.

Is there anything available in F31 that doesn’t explode? It looks like “peek” will work for animated GIFs, but I would prefer to be able to record to actual video files and I would like to record audio at the same time, rather than trying to mix it in afterwards.