Calculator Demo:
This example uses COXShape class 
Description: 
While Windows 3.1x APIs only offered support for rectangular windows, Windows 95 and Win NT 3.51+ implement an API function that makes creating and managing shaped windows a lot easier. This class encapsulates this function and offers a range of shapes you can give to your CWnd derived objects. 
Features:
•	Supplies the most commonly known shapes like STARS, ROUNDRECTS, ELLIPSES, TRIANGLES, PENTAGONS,... 
•	Uses multiple inheritance to make the interface as simple as possible 
•	Very easy to use and small code adjustment via a DECLARE/IMPLEMENT macro pair.