code: function (el, x, y) {
              var currentRegion = this.currentRegion,
                  highlightEnabled = !this.options.get('disableHighlight'),
                  newRegion;
              if (x > this.canvasWidth || y > this.canvasHeight || x < 0 || y < 0) {
                  return null;
              }
              newRegion = this.getRegion(el, x, y);
              if (currentRegion !== newRegion) {
                  if (currentRegion !== undefined && highlightEnabled) {
                      this.removeHighlight();
                  }
                  this.currentRegion = newRegion;
                  if (newRegion !== undefined && highlightEnabled) {
                      this.renderHighlight();
                  }
                  return true;
              }
              return false;
          }
docs: Highlight an item based on the moused-over x,y co-ordinate