code: protected final Color decodeColor(String key, float hOffset, float sOffset, float bOffset, int aOffset) {
          if (UIManager.getLookAndFeel() instanceof SeaGlassLookAndFeel) {
              SeaGlassLookAndFeel laf = (SeaGlassLookAndFeel) UIManager.getLookAndFeel();
  
              return laf.getDerivedColor(key, hOffset, sOffset, bOffset, aOffset, true);
          } else {
  
              // can not give a right answer as painter should not be used outside
              // of nimbus laf but do the best we can
              return Color.getHSBColor(hOffset, sOffset, bOffset);
          }
      }
docs: Decodes and returns a color, which is derived from a base color in UI
  defaults.
  
  @param  key     A key corresponding to the value in the UI Defaults table
  of UIManager where the base color is defined
  @param  hOffset The hue offset used for derivation.
  @param  sOffset The saturation offset used for derivation.
  @param  bOffset The brightness offset used for derivation.
  @param  aOffset The alpha offset used for derivation. Between 0...255
  
  @return The derived color, whos color value will change if the parent
  uiDefault color changes.