Hover over the top left to access the variables. They are currently set at the recommended levels. Press 'SPACE' to pick the color at cursor. The top color is the last picked color; and the ones below are the strength and values of the red, green, and blue channels.
I mainly made did this as a break from a different project, as well as figuring out how RGB and HSV color theory work together. Scratch's color detection is a little bit iffy at times, due to a lower sensetivity, when detecting color. It's nothing special really. I might make a version of this, but for HSV.