Here is an update to nTris-sdl with the following features:
1. sdl key auto-repeat as suggested by hoffa in a previous post.
2. support for dynamically changing the background. Use the 'key_b' to get something like shown below:
In principle, you can add as many backgrounds as you like. I provide 4 samples. Make sure they are transferred to the same folder as the executable.
3. LBNL, i've also cleaned up the source code. So it should be more readable now.
That's it. Cheers,