code: function () {
                      if (thisLayer.activeControl) {
                          if (thisLayer.activeControl === thisLayer.headingLeftControl) {
                              thisLayer.wwd.navigator.heading += thisLayer.headingIncrement;
                          } else if (thisLayer.activeControl === thisLayer.headingRightControl) {
                              thisLayer.wwd.navigator.heading -= thisLayer.headingIncrement;
                          }
                          thisLayer.wwd.redraw();
                          setTimeout(setRange, 50);
                      }
                  }
docs: capture 'this' for use in the function