Meld just updated from 3.20.4 to 3.22.0 (I have ~amd64 set for meld), and now meld uses client side decorations instead of allowing the window manager to handle that stuff. This is extremely annoying, since meld looks/acts differently than everything else and a lot of window operations are now unavailable for meld.
For now, I'm goint to revert to 3.20.4, but hopefully there's a way to get meld 3.22 to behave itself? -- Grant