Fired when a document is about to be added.  Can be canceled.
            
 Declaration Syntax
 Declaration Syntax| C# | Visual Basic | Visual C++ | 
public event AddDocumentEventHandler AddingDocument
Public Event AddingDocument As AddDocumentEventHandler
public: event AddDocumentEventHandler^ AddingDocument { void add (AddDocumentEventHandler^ value); void remove (AddDocumentEventHandler^ value); }