code: function(evt, view) {
  
          if (evt.type === 'mousedown' && evt.button === 2) {
              // handled as `contextmenu` type
              return true;
          }
  
          if (this.options.guard && this.options.guard(evt, view)) {
              return true;
          }
  
          if (evt.data && evt.data.guarded !== undefined) {
              return evt.data.guarded;
          }
  
          if (view && view.model && (view.model instanceof joint.dia.Cell)) {
              return false;
          }
  
          if (this.svg === evt.target || this.el === evt.target || $.contains(this.svg, evt.target)) {
              return false;
          }
  
          return true;    // Event guarded. Paper should not react on it in any way.
      }
docs: Guard the specified event. If the event is not interesting, guard returns `true`. Otherwise, it returns `false`.