Previously it used "contrast" and "brightness" values that were computed in strange ways. Now it behaves more like the other color computation functions and deals with the "flags" directly. Comparing many controls, colors on button frames in all states appear to be the same (or nearly the same, within 1-2 RGB values) before and after this change. Change-Id: Ia6d696c29fc76c73c88cc97af97ea45e1ff089ff Reviewed-on: https://review.haiku-os.org/c/haiku/+/9321 Reviewed-by: waddlesplash <[email protected]>