node.addChild(child);
Node childchild = new MyCompositeNode();
childchild.setOrigin(5, 5);
childchild.setSize(70, 70);
child.addChild(childchild);
// retrieve childchild
assertEquals(childchild, node.getChildAt(15, 20));
assertEquals(node, child.getParent());
assertEquals(child, childchild.getParent());