Tooltip not showing up over the Popup initially in Solaris

1. Run the application in both Solaris Sparc & Windows.
2. To kill the app, press ctrl+c, because this app will cover the entire desktop.
3. The JPanel that sits over the Popup has a tooltip attached to it. As the Popup emerges, the tooltip shows at wherever the mouse pointer is located in Windows platform, but it is not happening in Solaris. In solaris, the tooltip appears only after moving the mouse pointer once after the popup shows.

Platforms in which happens: Solaris Sparc, works okay in Windows.

% java -version
java version "1.4.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta-b58)
Java HotSpot(TM) Client VM (build 1.4.0-beta-b58, mixed mode)

Code used:
import java.awt.*;
import javax.swing.*;

public class poptest01 {
  JPanel panel;
  
  public poptest01() {
    panel = new JPanel(new BorderLayout());
    panel.setPreferredSize(Toolkit.getDefaultToolkit().getScreenSize());
    panel.setToolTipText("it is a panel!");
    
    PopupFactory factory = PopupFactory.getSharedInstance();
    Popup popup = factory.getPopup(null, panel, 0, 0);
    popup.show();
    /*try {
      Thread.sleep(2000);
    }
    catch (InterruptedException ie) {
      ie.printStackTrace();
    }*/
    //popup.hide();
  }
  
  public static void main(String args[]) {
    poptest01 s = new poptest01();
  }
}