code: public void setRenderOrder (int renderOrder)
      {
          if (_renderOrder != renderOrder) {
              _renderOrder = renderOrder;
              if (_mgr != null) {
                  _mgr.renderOrderDidChange(this);
                  invalidate();
              }
          }
      }
docs: Sets the render order associated with this media. Media can be rendered in two layers; those
  with negative render order and those with positive render order. In the same layer, they
  will be rendered according to their render order's cardinal value (least to greatest). Those
  with the same render order value will be rendered in arbitrary order.
  
  <p>This method may not be called during a tick.
  
  @see #HUD_LAYER