code: function(evt) {
          if(OpenLayers.Util.mouseLeft(evt, this.map.viewPortDiv)) {
              this.stoppedDown = this.stopDown;
              this.mouseDown = false;
          }
      }
docs: Method: mouseout
  Handle mouse out.  For better user experience reset mouseDown
  and stoppedDown when the mouse leaves the map viewport.
  
  Parameters:
  evt - {Event} The browser event