Sorry if this has already been answered, I had a look but couldn't find anything exact.
I'm trying to make an oldschool 2d pixel game that i'd like to keep at a small resolution and 4:3 ratio to keep the pixels large but still support modern resolutions. However for widescreen resolutions I was thinking of making it so that it displayed a graphic as a border instead of black bars when full screen and/or windowed. An example graphic might be the graphics surrounding a screen on an arcade machine.
Any help with this would be much appreciated.