You draw on the screen using the touch pen and change the color by holding down Y, X, A and using Up and Down to add or remove Red, Green and Blue to change the colour of the pen.
It uses a library called "PA_Lib" which as I remember back in 2008 was pretty good, but it seems like things have moved on in the 5 years since I created this program and other libraries and frameworks are more mature and well established.
Regardless the code is really simple, there are only 2 functions:
- main - which controls the program and is the starting point
- ColorUpDownControl - which controls setting the color
The main function is below, but if you want to download it and have a go, I've uploaded all the source, libraries, build utilities and executable.