Layout help

[mvogt juptech com]

I have recently been investigating GTK+, looking at the possibility of
porting an existing application which was built using a toolkit with fixed
layout.  I am having trouble recreating some of the correct designs in
GTK+, because of the dynamic layouts.  I realise that I can prevent this as
a last resort, but I would like to achieve a best-of-both-worlds result, if
possible.

So, are there any web pages which contain tips or tricks for controlling
layout in fine detail (other than the documentation on www.gtk.org)?

An example of what I would like to be able to do: constrain the top half of
a vbox to remain at the original vertical size, while allowing a resize to
change the vertical dimension of the lower half of the vbox.

Thanks,
Matt.