code: function mxRectangle(x, y, width, height)
  {
  	mxPoint.call(this, x, y);
  
  	this.width = (width != null) ? width : 0;
  	this.height = (height != null) ? height : 0;
  }
docs: Copyright (c) 2006-2015, JGraph Ltd
  Copyright (c) 2006-2015, Gaudenz Alder
   
  Class: mxRectangle
  
  Extends <mxPoint> to implement a 2-dimensional rectangle with double
  precision coordinates.
  
  Constructor: mxRectangle
  
  Constructs a new rectangle for the optional parameters. If no parameters
  are given then the respective default values are used.