code: private void initComponents() {
          // Avoid warning on Mac OS X when changing the alpha
          getRootPane().putClientProperty("apple.awt.draggableWindowBackground", Boolean.FALSE);
  
          toolTip = new JToolTip();
          toolTip.addMouseListener(new TransparencyAdapter());
  
          owner.addComponentListener(locationAdapter);
          owner.addAncestorListener(locationAdapter);
  
          getRootPane().setWindowDecorationStyle(JRootPane.NONE); // Just in case...
          setFocusable(false); // Just in case...
          setFocusableWindowState(false);
          setContentPane(toolTip);
          pack(); // Seems to help for the very first setVisible(true) when window transparency is on
      }
docs: Initializes the components of the tooltip window.