code: function(evt) {
          // Feature selection is only done with a left click. Other handlers may stop the
          // propagation of left-click mousedown events but not right-click mousedown events.
          // This mismatch causes problems when comparing the location of the down and up
          // events in the click function so it is important ignore right-clicks.
          if (OpenLayers.Event.isLeftClick(evt) || OpenLayers.Event.isSingleTouch(evt)) {
              this.down = evt.xy;
          }
          return this.handle(evt) ? !this.stopDown : true;
      }
docs: Method: mousedown
  Handle mouse down.  Stop propagation if a feature is targeted by this
  event (stops map dragging during feature selection).
  
  Parameters:
  evt - {Event}