The third button. If the form was red, make it go green. If the form was green, make it go yellow. If the form was yellow, make it go red. Don't respond to any other colour.
Task Add a fourth button.
Make it change the colours in any way you like to design. Use on-line help to find out what colours are available. This program uses two image controls and two timers. Use windows paintbrush to draw both images. There is a desert island and a shark fin.