🚀 go-pugleaf

I have a JPanel (a)  that contains different other JPanels (b), one at a
time, and I change the conent of panel a dynamically according to menu
selections. My problem is that when I change the panels b the panel a won't
redraw itself. I have tried various combinations of invalidate, validate,
revalidate, etc., as in the code included below:

    a.removeAll();
    b.setVisible(true);
    a.add(b, "Center");
    b.validate();
    a.invalidate();
    a.validate();
    a.revalidate();

With all these validate-methods, the panel a still don't redraw itself with
the correct content b. It works the first time I select a panel, but later I
don't work.

What is the correct way to solve such a problem?

By the way, I use JDK 1.1.7 and Swing 1.0.3, but the problem is the same
with JDK 1.1.6_Borland and Swing 1.0.1.

-Frode