// f modifies original content pane
// f: Component -> Component
static JSplitPane addToWindowSplitRight_f(Component c, Component toAdd, O f) {
  JFrame frame = getFrame(c);
  JSplitPane sp;
  frame.setContentPane(sp = jhsplit((Component) callF(f, frame.getContentPane()), toAdd));
  revalidate(frame);
  ret sp;
}