sclass StackLayouter extends F1<Container, Dimension> {
  Map<Component, Int> heights = weakHashMap();
  int gap = 5;
  //int defaultHeight = 50;
  int preferredWidth = 300;
  bool maximizeIfSingleComponent = true;
  
  Dimension get(Container parent) {
    L<Component> l = getComponents(parent);
    Insets insets = unnullInsets(parent.getInsets());
    Dimension size = parent.getSize();
    ifdef StackLayouter_debug
      print("StackLayouter: n=" + l(l) + ", insets=" + insets + ", size=" + size);
    endifdef
    int y = insets.top;
    int width = size.width-insets.left-insets.right;
    for (Component c : l) {
      Int H;
      if (maximizeIfSingleComponent && l(l) == 1) {
        ifdef StackLayouter_debug
          print("StackLayouter maximizing!");
        endifdef
        H = size.height-insets.bottom-y;
      } else
        H = heights.get(c);
      int h = H != null ? H : c.getPreferredSize().height;
      c.setBounds(insets.left, y, width, h);
      y += h+gap;
      ifdef StackLayouter_debug
        print("StackLayouter: y=" + y + ", h=" + h);
      endifdef
    }
    
    // return preferred size (hm.)
    ret new Dimension(preferredWidth, max(50 /* XXX */, y+insets.bottom-gap));
  };
}

Began life as a copy of #1022754