alignToContainerYLayout: Layouter = (layout, containerFrame) => {
  return layout.map(layoutInfo => ({
    ...layoutInfo,
    frame: {
      origin: {
        x: layoutInfo.frame.origin.x,
        y: containerFrame.origin.y,
      },
      size: layoutInfo.frame.size,
    },
  }));
}
A layouter that aligns all frames' tops to the container frame's top.