The mouse position has been fixed and behaves properly in a scaled window. The game window can now be changed to any size and aspect ratio. Which is nice to have, since it makes using the debug tools a lot easier. And I can now run the game in a smaller window again and still be able to select things.
I did want to also implement some other feature. Making it possible to scale the window while keeping the correct aspect ratio. However I figured I don’t need it that much and rather spend the time on some household things. Monday I can look into the other videos, since there are some OpenGL fixes in there that may be essential. As well as multiple render targets which is still needed for platforms like the Nintendo 3DS. It’s just a question of do I implement it now or do I come back to it later. After I’ve done the first or second playtest.