'Override the XBlock.has_support method to return appropriate
value for the multi-device functionality.
Returns whether the given view has support for the given functionality.'

def has_support(self, view, functionality):

    if (functionality == 'multi_device'):
        types = self.problem_types
        return ((types is not None) and all((responsetypes.registry.get_class_for_tag(tag).multi_device_support for tag in types)))
    return False
