Sets the drag drop filter for this widget.
        
        :warning    The dragdropfilter is stored as a weak-reference, so using \
                    mutable methods will not be stored well.  Things like \
                    instancemethods will not hold their pointer after they \
                    leave the scope that is being used.  Instead, use a \
                    classmethod or staticmethod to define the dragdropfilter.
        
        :param      ddFilter | <function> || <method> || None

def setDragDropFilter( self, ddFilter ):
        """
        Sets the drag drop filter for this widget.
        
        :warning    The dragdropfilter is stored as a weak-reference, so using \
                    mutable methods will not be stored well.  Things like \
                    instancemethods will not hold their pointer after they \
                    leave the scope that is being used.  Instead, use a \
                    classmethod or staticmethod to define the dragdropfilter.
        
        :param      ddFilter | <function> || <method> || None
        """
        if ddFilter:
            self._dragDropFilterRef = weakref.ref(ddFilter)
        else:
            self._dragDropFilterRef = None