Virtual base class constructor

[George2]

Hello everyone,


From MSDN virtual base class reference, what means "If a derived class overrides a virtual function that it inherits from a virtual base class, and if a constructor or a destructor for the derived base class calls that function using a pointer to the virtual base class, the compiler may introduce additional hidden "vtordisp" fields into the classes with virtual bases."

I do not understand why an additional hidden filed is needed?

http://msdn2.microsoft.com/en-us/library/wcz57btd.aspx#Mtps_DropDownFilterText


thanks in advance,
George