Added a function to update sizegroups in multiple passes, this
way the width and height can be updated in the sizegroups after
querying the extended layout implementor for these.
Implemented this in GtkExtendedLayout, sizegroups should be working reasonably now.
This commit changes gtk_extended_layout_get_desired_size() for
per dimension variants. Furthermore this commit reverts the actions
done in size-groups for now as it needs a different approach.
The natural width/height parameters added to aux_info have been changed
for a per width cache for heights and a per height cache for widths.
gtk-demo is still working, currently sizegroups are not taken
into account as mentioned above - size groups need to be alerted both
when the widths and heights are updated independantly and then that
information needs to repropagate also to other extended layout implementors.
Added an indicator telling whether a widget prefers to be allocated
as height-for-width or width-for-height. Usually this depends on the
orientation of a container or the nature of a content widget like GtkLabel.
This indicator is only used in the seldom case where a parent is allocating
free space to the child and the child can flow in either direction, GtkWindow
and GtkScrolledWindow are users of this api.
As it is not allowed to called gtk_extended_layout_get_desired_size()
on a GtkWidget directly; gtk_widget_get_desired_size() was really an
ambiguous api. This patch removes the added GtkWidget api, calls
the appropriate sizegroup code which in turn envokes the interface
vtable, this patch also accordingly makes GtkWidget a prerequisite
of GtkExtendedLayout (the api doesnt work for cell renderers anyway,
patch comming...).
