def add_from_xmlnode(self, element):
        """Load ui definition from xml.etree.Element node."""
        if self.tree is None:
            root = ET.Element('interface')
            root.append(element)
            self.tree = tree = ET.ElementTree(root)
            self.root = tree.getroot()
            self.objects = {}
            # ET.dump(tree)
        else:
            # TODO: append to current tree
            pass
Load ui definition from xml.etree.Element node.