aah, thanks for the GIF. I've definitely seen this issue before. It seems to be a bug in the API I used for handing window stuff (SDL 1.0). Hoping to fix it by switching to a newer version (a friend tells me the are on SDL 3 already!) someday. For now, if you haven't already figured it out, the workaround is to click off the window, then click back on the window's title bar. Not sure why, but that usually gets it responding again. I'm guessing the other issue you saw is probably just another variation of the same bug.
ps
have the feature working, busy with some IRL stuff this week, hope to package up a new build sometime next week.