When I am running a standalone version of the game, in windowed mode, I can drag the corner of the window to resize it. The resolution scales correctly once I release the mouse.
The problem is that if I leave that window for a moment, and then click to focus it again, the window reverts back to the original size. How can I make it keep it’s size?
Do me a favor and give this a try in the 4.15 Preview. This sounds similar to a bug that was addressed in 4.15. When I tested this myself in 4.15 Preview 3, it seemed to be working as intended.