is.$.toggleButton.classList.remove('dragging');
      var old = this.checked;
      this.checked = Math.abs(this._x) > this._w / 2;
      if (this.checked !== old) {
        this.fire('change');
      }
    },
    
    checkedChanged: function() {
      this.setAttribute('aria-pressed', Boolean(this.checked));
      this.fire('core-change');
    }

  });

</script>
</polymer-element>
