When you run the project, you should see a gap moving around the circle. Full-screen the stage, and stare at the cross. In a few seconds, you should see a green spot. Keep staring at the cross, and the green spot will erase the pink spots. Look away, and you’ll see the gap again.
When you stare at something for a long time, the color receptors in your brain start to tire out, and your brain starts to tune colors out, causing that green spot you see.
