// runnable takes an argument
static void onLeftClick(JComponent c, final O runnable) {
  c.addMouseListener(leftClickMouseAdapter(runnable));
}

// runnable takes no args
static TrayIcon onLeftClick(final TrayIcon c, final O runnable) {
  swing {
    c.addMouseListener(leftClickMouseAdapter_noPt(runnable));
  }
  ret c;
}