Just click the green flag and click that button (It might not work at the first click)!
I first had the idea of making this project using costume effects. However, it did not work as intended, so I tried to use pen instead, since I set my variables for hue-saturation-brightness and the pen color effects had the exact same things. Problem solved! Music: Undertale OST - Pathetic House ~~How does this work?~~ I coded the button to pick a random number between 0 and 100 for the hue, saturation, and brightness variables. In the other sprite, there's code to set the color "according to the variables" and just.... Show it using the "Pen down" button.