code: function(feature) {
          var isPoint = feature.geometry.CLASS_NAME ==
                  'OpenLayers.Geometry.Point';
          if (!this.standalone &&
                  ((!feature._sketch && isPoint) || !feature._sketch)) {
              if (this.toggle && this.feature === feature) {
                  // mark feature for unselection
                  this._unselect = feature;
              }
              this.selectFeature(feature);
          }
          if (feature._sketch || isPoint) {
              // feature is a drag or virtual handle or point
              this.vertex = feature;
              this.handlers.drag.stopDown = true;
          }
      }
docs: Method: dragStart
  Called by the drag handler before a feature is dragged.  This method is
  used to differentiate between points and vertices
  of higher order geometries.
  
  Parameters:
  feature - {<OpenLayers.Feature.Vector>} The point or vertex about to be
  dragged.