Parses a handle and returns the guid and state.
virtual bool SplitHandle( const TCHAR* pszHandle, std::tstring& strKey, long& lState );
A handle, as displayed in an Excel cell.
The key that is extracted from the handle is placed into strKey.
The key is always in the form of a GUID, e.g.:
The state number that is extracted from the handle is placed into lState.
Returns true if the conversion succeeded, or false if the handle could not be successfully parsed.
This method is called by the HandleCache<T> object when it converts a handle argument into a pointer to an object of type T.