I know that this has been asked about before, but I don't know if this is something we can do yet or not (so if this is possible, please forgive me and point me in the direction on how to do this).
I would like to be able to change the frame graphics around the 3D viewport. This has been discussed before, and would allow us to make the graphics that come out of the viewport like the FRUA dolphin pic, or to allow us to change the Dragonlance moons below the viewport
I envision another idea entirely which would allow making a mini-game, which I want to make a demo for.
ST -- inspired to make a demo mod