I don't really understand either the question or the answer - but :

a) The picture certainly doesn't look like that of a GridLayout. Is it a
GridBagLayout ? In which case they are totally different beasts.

b) Calling setPreferredSize() is evil - don't ever use it if you can.
(See point (c) for the reason).

c) As regards to the answer to the question : The whole point of
LayoutManagers is that a container should be able to figure out how big
it ought to be based on the size of its children (and possibly
grandchildren - and so on) irrespective of the platform, user
preferences of font size etc. When you try setting sizes that you think
will make the children fit, you're defeating the purpose of
LayoutManagers altogether. In which case one could as well have used a
null LayoutManager (God forbid).

BK