Nope, you can do whatever size you want. Only few parts have restricted by size.
Can't tell, I don't have supporter. But might be true. Test it on map that doesn't have background. https://osu.ppy.sh/s/2934Rei Hakurei wrote:
Just asking,
is Version:2 behaviour on selecting a song (which is the background of the map itself is not loaded yet) uses menu-background.jpg instead playfield.png ?
i hope its not a bug tho.