VectorCanvas.prototype.createGroup = function (isRoot) {
  var node;
  if (this.mode === 'svg') {
    node = this.createSvgNode('g');
  } else {
    node = this.createVmlNode('group');
    node.style.width = this.width + 'px';
    node.style.height = this.height + 'px';
    node.style.left = '0px';
    node.style.top = '0px';
    node.coordorigin = '0 0';
    node.coordsize = this.width + ' ' + this.height;
  }

  if (isRoot) {
    this.rootGroup = node;
  }
  return node;
};