Calculates the minimum and natural height
for the area if the passed @context would be allocated the given width.
When implementing this virtual method it is safe to assume that @context
has already stored the aligned cell widths for every gtk.tree_model.TreeModel row
that @context will be allocated for since this information was stored
at GtkCellAreaClass.get_preferred_width() time. This virtual method
should also store any necessary alignments of cell heights for the
case that the context is allocated a height.
Calculates the minimum and natural height for the area if the passed @context would be allocated the given width. When implementing this virtual method it is safe to assume that @context has already stored the aligned cell widths for every gtk.tree_model.TreeModel row that @context will be allocated for since this information was stored at GtkCellAreaClass.get_preferred_width() time. This virtual method should also store any necessary alignments of cell heights for the case that the context is allocated a height.