+ //=============================================
+ typedef boost::signal<void (bool)> ValidationSignalType;
+ typedef ValidationSignalType::slot_function_type ValidationCallbackType;
+ //=============================================
+
+ //==================================================================
+ /// Adds the function f to the list of functions to call
+ /// when the addition progresses.
+ /// f is of type ProgressCallbackType which is:
+ /// void (*ProgressCallbackType)(Progress&)
+ /// To pass a member function 'f' of an instance 'c' of a class 'C'
+ /// as callback you have to 'bind' it, i.e. call:
+ /// ConnectValidationObserver ( boost::bind( &C::f , c, _1 ) );
+ void ConnectValidationObserver(ValidationCallbackType callback);
+ //==================================================================
+