def child_added(self, child):
        super(Container, self).child_added(child)
        if isinstance(child, ConstraintsWidget):
            self.request_relayout()
Upload any file, expect a 200 and auto mime type
dataset/ETHPy150Open ContinuumIO/ashiba/enaml/enaml/widgets/container.py/Container.child_added--crossover with--dataset/ETHPy150Open thekad/pasttle/tests/suites/functional.py/FunctionalTest.test_upload_file_auto_syntax