There’s a weird bug in Ubuntu 24.04 where some windows cannot be resized if you’ve got your system set to automatically log in when you boot up the computer.
Odd.
If you log out and log back in, everything works fine again. But I don’t want to have to do that. So I delved into shortcuts and turns out in Ubuntu’s GUI, Gnome, if you hold down the Super-key (Windows-key on a Windows-themed keyboard) and drag the edge of the window with a mousewheel click (or middle-click if you’re still rocking a 3-button mouse) you can resize the window in either direction.
Handy.