Extending objects in Excel 2003 with VBA
 

I just want to find out whether it is possible to extend or override methods
or properties of objects (specifically I'd like to over-ride the double-click
method of a selected standard shape object, or create an extension of the
shape object).
- in Excel 2003?
- in later versions?

From what I see I guess the answer is No but I'd like that confirmed.