code: protected Icon getSizingIcon(AbstractButton b) {
          // NOTE: this is slightly different than BasicButtonUI, where it
          // would just use getIcon, but this should be ok.
          Icon icon = (b.isEnabled() || b.getDisabledIcon() == null) ? b.getIcon() : b.getDisabledIcon();
  
          if (icon == null) {
              icon = getDefaultIcon(b);
          }
  
          return icon;
      }
docs: Returns the Icon used in calculating the pref/min/max size.
  
  @param  b DOCUMENT ME!
  
  @return DOCUMENT ME!