code: function(evt) {
  
          evt.preventDefault();
  
          // magnetpointerdblclick can stop propagation
  
          evt = joint.util.normalizeEvent(evt);
  
          var view = this.findView(evt.target);
          if (this.guard(evt, view)) return;
  
          var localPoint = this.snapToGrid({ x: evt.clientX, y: evt.clientY });
  
          if (view) {
              view.pointerdblclick(evt, localPoint.x, localPoint.y);
  
          } else {
              this.trigger('blank:pointerdblclick', evt, localPoint.x, localPoint.y);
          }
      }
docs: Interaction. ------------