Called by the framework when the add-in is registered with the Excel Add-in Manager
virtual BOOL OnXllRegisterEx( );
This function is called whenever a user registers the add-in using the Excel Tools - Add-ins dialog. You can use this event to demand, for example, registration information from the user. You should return FALSE if some problem arises during this handling, and the registration of the XLL will be cancelled.
Note that since the XLL can be opened directly using the File - Open menu option, this event will not always take place.
The default implementation of this function does nothing and returns TRUE.