// also works when using centering of the component,
// e.g. through jscroll_center_borderless
svoid onEnclosingScrollPaneResize(JComponent c, Runnable r) {
  new OnEnclosingScrollPaneResize(c, r).install();
}

srecord noeq OnEnclosingScrollPaneResize(JComponent c, Runnable r) {
  ComponentAdapter listener;
  settable bool debug;
  
  void install {
    if (r == null) ret;
    bindToComponent(c, -> {
      viewport = getParent(getParent(c));
      if (viewport instanceof JViewport) {
        listener = new ComponentAdapter {
          public void componentResized(ComponentEvent e) {
            if (debug) print("Viewport resized");
            pcallF(r);
          }
        };
        c.addComponentListener(listener);
      }
    }, -> {
      if (listener != null)
        viewport?.removeComponentListener(listener);
    });
  }
}