docs: function (handRef)
      {
          // this must be done in the Idle loop so that we don't change
          // the handlers during iteration
          this.removeHandlers.push(handRef);
          // If a handler is being deleted while it is being added,
          // prevent it from getting added
          var i = this.addHandlers.indexOf(handRef);
          if (i >= 0) {
              this.addHandlers.splice(i, 1);
          }
      }