The first solution I found was to make sure the window started off in the top left corner of the screen. But this quickly failed. Then someone on reddit offered this solution:
$ nano /usr/share/applications/minecraft-launcher.desktop
Exec=env GTK_CSD=0 minecraft-launcher
Alternatively, running $ env GTK_CSD=0 minecraft-launcher will also ...
I solved the problem.
If you do play Minecraft, the launcher for the game has an issue with it's window shadow. This can be fixed easily. Type in this command in terminal:
sudo nano /usr/share/applications/minecraft-launcher.desktop
find line "Exec"
and add: env GTK_CSD=0
save file and lunch minecraft