code: function () {
          if ( this.viewport ) {
              var containerSize = new $.Point(
                      (this.container.clientWidth === 0 ? 1 : this.container.clientWidth),
                      (this.container.clientHeight === 0 ? 1 : this.container.clientHeight)
                  );
  
              if ( !containerSize.equals( this.oldContainerSize ) ) {
                  this.viewport.resize( containerSize, true );
                  this.viewport.goHome(true);
                  this.oldContainerSize = containerSize;
                  this.drawer.clear();
                  this.world.draw();
              }
          }
      }
docs: Used to notify the navigator when its size has changed.
  Especially useful when {@link OpenSeadragon.Options}.navigatorAutoResize is set to false and the navigator is resizable.
  @function