static <A extends JComponent> A draggableFloatingComponent(final A a) {
  final new Var<Pt> pt; // where in the component mouse was clicked
  
  addMouseListener(a, new MouseAdapter { 
    public void mousePressed(MouseEvent e) {
      if (e.getButton() == MouseEvent.BUTTON1)
        pt.set(pt(e.getX(), e.getY()));
    }
    
    public void mouseReleased(MouseEvent e) {
      if (e.getButton() == MouseEvent.BUTTON1) {
        //a.setLocation(e.getX()+pt->x, e.getY()+pt->y);
        pt.set(null);
      }
    }
  });
  
  addMouseMotionListener(a, new MouseMotionAdapter {
    public void mouseDragged(MouseEvent e) {
      Point scr = e.getLocationOnScreen();
      Point p = a.getParent().getLocationOnScreen();
      a.setLocation(scr.x-pt->x-p.x, scr.y-pt->y-p.y);
    }
  });
  
  ret a;
}