A simple paint program with the options to draw, draw with rainbow colors, use different sizes, clear the screen, and use the eraser!
The only thing I have to explain is the eraser. It's a trick. the only thing we are doing is simply drawing white lines over the colored lines. You can find this trick using a different background, such as black. And then is it a simple matter of adding an if/else condition within the block that changes color! If ?eraser = 0: change color by PEN COLOR. Else; set the pen color to #fffff (hex color for white)