Sometimes what's needed is multiple instances of the same
LayoutManager. For instance, consider the calculator applet
again.
On the one hand this looks like it should be simple to implement
in Java. After all it's just eighteen buttons and a
TextField. On the other hand although most of the keys are
the same size, two of the keys and the TextField are
oversized. You could almost use a GridLayout, but not
quite. Panels are one way to solve this problem.