add _gtk_rbtree_set_fixed_height()

add _gtk_rbtree_set_fixed_height()

Wed Mar 20 22:59:23 2002  Kristian Rietveld  <kris@gtk.org>

        * gtk/gtkrbtree.[ch]: add _gtk_rbtree_set_fixed_height()

        * gtk/gtktreeprivate.h: add fixed_height_check field

        * gtk/gtktreeview.c (gtk_tree_view_init): initialize
        scroll_sync_timer and fixed_height_check
        (do_validate_rows): add fixed_height_check. If all validated rows
        in the first cycle have the same height, then we set that height for
        the entire tree. This is some sort of 'fake' optimization, but helps
        a lot for the common case. We keep validating the entire tree in
        the background though.
        (gtk_tree_view_set_model): reset fixed_height_check