This is sometimes needed for cases where rows need to share
alignments in one orientation but may be separately grouped
in the opposing orientation.
For instance, gtk.icon_view.IconView creates all icons (rows) to have
the same width and the cells theirin to have the same
horizontal alignments. However each row of icons may have
a separate collective height. gtk.icon_view.IconView uses this to
request the heights of each row based on a context which
was already used to request all the row widths that are
to be displayed.
This is sometimes needed for cases where rows need to share alignments in one orientation but may be separately grouped in the opposing orientation.
For instance, gtk.icon_view.IconView creates all icons (rows) to have the same width and the cells theirin to have the same horizontal alignments. However each row of icons may have a separate collective height. gtk.icon_view.IconView uses this to request the heights of each row based on a context which was already used to request all the row widths that are to be displayed.