Comment 3 for bug 165666

I agree with testerus that changes should be kept to a
minimum. With several different objects selected, the color
displayed by the dialog is not an actual color anyway, but
is an average, so it makes little sense to assign it to all
object. On the other hand, assigning only the changed
slider's value would allow for very useful effects, e.g.
reducing the saturation of all selected objects without
changing their hue, by dragging the S slider on HSV tab.