Help with getPreferredSize()

[Geoffrey Falk]

I need some help. I am writing a fractal generator. The main window has a BorderLayout with some controls in the NORTH and SOUTH fields. The CENTER field has a Canvas component with a preferred size.
The problem is, how do I calculate the correct size of the containing Frame? If I call getPreferredSize() on the NORTH and SOUTH components from the Frame constructor, it is returning zero. I think this is because they haven't been initialized ?
More generally, I don't understand the process of initialization of AWT components. Can somebody please explain to me in general how getPreferredSize() works, how it is used by the LayoutManager, etc? Thanks..