set first_cell to FALSE after first iteration

set first_cell to FALSE after first iteration

Fri Mar  1 23:59:35 2002  Kristian Rietveld  <kris@gtk.org>

        * gtk/gtktreeviewcolumn.c (gtk_tree_view_column_cell_get_size): set
        first_cell to FALSE after first iteration

        * gtk/gtktreeview.c (validate_visible_area): reduce usage of
        GTK_RBNODE_GET_HEIGHT, check for node != NULL,
        (gtk_tree_view_top_row_to_dy): remove call to gtk_adjustment_changed
        (gtk_tree_view_search_iter): select iter after scrolling