Recursively cancel all threaded background processes of this Callable.
            This is called automatically for actions if program deactivates.

def cancel(self, caller):
        """
            Recursively cancel all threaded background processes of this Callable.
            This is called automatically for actions if program deactivates.
        """
        for o in {i for i in self.children if isinstance(i, AbstractCallable)}:
            o.cancel(caller)