GtkFixed child control resizing

["Atanas Atanasov" <thenasko gmail com>]

I have a GtkWindow with a single GtkFixedChild. Then all the rest of
the interface goes into the GtkFixed with exact positions which I can
set through gtk_fixed_put or gtk_fixed_move. Suppose I have a GtkLabel
child. I would like to be able to set its size and apply a text
alignment through gtk_label_set_justify - for example centered.
However I do not see how this can be done since GTK is a layout widget
toolkit and one rarely works with specific coordinates in this case.
Also I would like to set the vertical alignment of the text.

Thanks in advance,
Atanas