Name: skT88420 Date: 04/21/99


When a JDialog is popped up from a menu item, the popup cannot
be used as the component for setting the dialog location.

Specifically, I had an ActionListener to a JMenuItem that looks
like this:

   public void actionPerformed (ActionEvent e)
   {
      Component sourceComponent = null;

      if (e.getSource () instanceof Component)
         sourceComponent = (Component) e.getSource ();

      JOptionPane.showMessageDialog
         (sourceComponent,
         name + " " + versionNumber + "\n" + versionDate,
         "About " + name,
         JOptionPane.INFORMATION_MESSAGE);
   }

and the popup was always in the center of the screen. I tracked
problem to where JDialog has a loop to find the window that
contains the component. This logic does not allow for the
fact that JPopupMenus are not in the parent chain of their
windows. I changed my code to the following, which worked fine.
I recommend this change to the JDialog logic. Thank you.

New code:

   public void actionPerformed (ActionEvent e)
   {
      Component sourceWindow = null;

      if (e.getSource () instanceof Component)
         sourceWindow = getWindow ((Component) e.getSource ());

      JOptionPane.showMessageDialog
         (sourceComponent,
         name + " " + versionNumber + "\n" + versionDate,
         "About " + name,
         JOptionPane.INFORMATION_MESSAGE);
   }

   Component getWindow (Component c)
   {
      // This is copied from JDialog, except that it fixes
      // the bug caused by JPopupMenu

      boolean trace = true;
      Component root = null;

      if (c != null)
      {
         if (c instanceof Window || c instanceof Applet)
         {
            if (trace)
               System.out.println (c.getClass ().getName ());
            root = c;
         }
         else
         {
            Component parent;
            for (parent = getParent (c);
                 parent != null ;
                 parent = getParent (parent))
            {
               if (trace && parent == null)
                  System.out.println ("null");
               else if (trace)
                  System.out.println (parent.getClass ().getName ());

               if (parent instanceof Window || parent instanceof Applet)
               {
                  root = parent;
                  break;
               }
            }
         }
      }
      else if (trace)
         System.out.println ("null");

      return root;
   }

   Component getParent (Component c)
   {
      if (c instanceof JPopupMenu)
         return ((JPopupMenu) c).getInvoker ();
      else
         return c.getParent ();
   }
(Review ID: 53237)
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