I also have this problem on latest Ubuntu-MATE 18.04.2 LTS, does not happen on Xubuntu, Lubuntu or any other Ubuntu flavor. Only way back is to toggle "Use system title bar and borders".
I also have this problem on latest Ubuntu-MATE 18.04.2 LTS, does not happen on Xubuntu, Lubuntu or any other Ubuntu flavor. Only way back is to toggle "Use system title bar and borders".