I've noticed that certain settings for the dock restrict the movement of windows on dual-monitor setups.
As this wasn't my final setup, it's not of particular concern to me, however hopefully this is easy to fix in the next MATE.
The basic gist is in the following screenshot: I cannot move any window "past" the dock, the title bar corners seem to catch.
The settings appear to involve:
- Any dock that isn't set to hide.
- A dual monitor that is placed past the dock.
Seems like this has also been around since 20.04: Bottom Panel Bug with Dual Screen Displays 20.04. The first bug report linked in this post suggests that a not-hidden plank dock on a shared edge is not supported 