Returns the reference of the active cell in the selection as an external reference
[C++]
static int ActiveCell(
   CXlOper& xloRef
);
A reference to a CXlOper that will contain the active cell if the function succeeds.
Zero if the function has been called successfully; non-zero
            if the function could not be called.
            See Error codes for a list
            of return values.
See the Microsoft Excel on-line Help for full details about
            this function.
Header: xlfuncs.h