text: function TicketSizeExpression() {
  	StyleExpression.call(this);
  }
  TicketSizeExpression.prototype = Object.create(StyleExpression.prototype);
  
  TicketSizeExpression.prototype.interpret = function (context) {
  	StyleExpression.prototype.interpret.call(this, context);
  	var value = this._getExpression("ticketSize"),
  		sizeParts = value.split("x");
  	this._setContextValue("width", sizeParts[0] + "px");
  	this._setContextValue("height", sizeParts[1] + "px");
  };