Compressing the size of components (packing)

In Java, in my younger years, i used to
call a method pack() after adding the
components to my window. It caused the
layout manager to set the desired size
(preferredSize, optimalSize, whatever
it's called) to all children.

I can't find such a thing in WPF,
though. How do i compact my layout?
As of now, i manually set properties
of ColumnDefinition objects and
RowDefinition objects, which seems to
be working but not excellent.

--
Regards
Konrad Viltersten
--------------------------------
sleep - a substitute for coffee for the poor
ambition - lack of sense to be lazy