RGBColor expression displays as a little square, showing the color. I just found that this little square is both a tooltip and a button. It seems to be new in version 10. When I click on it, I get a user interface showing three sliders for changing red, green and blue and a slider for the opacity. This gives a very nice way of changing the displayed color, in my opinion much simpler and more flexible than
I can use this interface in a very primitive way. Type
Do not evaluate, but evaluate the argument
RGBColor[0,0,0] in place so that a black square appears. Click on this button, construct the color and press shift-enter.
Is a better way to use this interface, similar to
Personally, I prefer the just discovered interface highly over those of ColorSlider and ColorSetter. The latter two, however, allow a dynamic argument, and that is what I am looking for with the new interface.