I currently play on 2 screens. One is my laptop and a separate monitor. I have set the separate monitor as the main screen. When I start Minecraft and set to full-screen mode, only part of the screen is covered with the game, even though I have previously maximized the window. The window is exactly the size of the laptop screen. Other programs do not have this problem.
I hope I have made my problem understandable. Can someone help me there?
Keep the Minecraft window small and press F11 within a world / server.
Or
Set the resolution in the MC Launcher to the resolution of your monitor then you get (in the best case) a full-screen window "without frame"
Probably Java (OpenGL) recognizes the wrong monitor as the main monitor.
Maybe the tip of the bug-tracker helps you to make the following settings with the right-click on the launcher:
Thank you, that worked.