The standard color wheel -- which you'll see in lots of apps -- doesn't have an OK button. I suppose the thought is you can move the little black square around until you find the color you like. Wherever you leave that square, it's the color you'll get. The top of that windoid has four other ways of selecting colors. If you don't like the wheel, you can use sliders, a pre-selected list, an input jpg or crayons.
mt