static new ThreadLocal<Bool> addInternalFrame_dontSelect;
static new ThreadLocal<Int> addInternalFrame_layer;
static new ThreadLocal<Bool> addInternalFrame_toBack;

static JInternalFrame addInternalFrame(final JDesktopPane desktop, fS title, final int x, final int y, final int w, final int h) {
  ret addInternalFrame(desktop, title, x, y, w, h, null);
}

static JInternalFrame addInternalFrame(final JDesktopPane desktop, fS title, final int x, final int y, final int w, final int h, final Component contents) {
  ret addInternalFrame(desktop, title, rect(x, y, w, h), contents);
}

static JInternalFrame addInternalFrame(final JDesktopPane desktop, fS title, final Component contents) {
  ret addInternalFrame(desktop, title, null, contents);
}

static JInternalFrame addInternalFrame(final JDesktopPane desktop, fS title, final Rect r, final Component contents) {
  final bool dontSelect = isTrue(optParam(addInternalFrame_dontSelect));
  final bool toBack = isTrue(optParam(addInternalFrame_toBack));
  final Int layer = optParam(addInternalFrame_layer);
  ret swing(func -> JInternalFrame {
    JInternalFrame frame;
    if (contents instanceof JInternalFrame)
      frame = (JInternalFrame) contents;
    else {
      frame = jInternalFrame(title);
      setInternalFrameContents(frame, contents);
    }
    frame.setVisible(true);
    desktop.add(frame, layer);
    if (r != null)
      setBounds(frame, r);
    else
      internalFrameDefaultPosition(frame);
    if (dontSelect)
      if (toBack)
        frame.toBack();
      else
        frame.toFront();
    else
      frame.setSelected(true);
    ret fixInternalFrame(frame);
  });
}

static JInternalFrame addInternalFrame(JDesktopPane desktop, S title) {
  ret addInternalFrame(desktop, title, jpanel());
}