new function, (validate_visible_area): when a node is validated, only
2006-04-26 Kristian Rietveld <kris@imendio.com>
* gtk/gtktreeview.c (node_is_visible): new function,
(validate_visible_area): when a node is validated, only queue a
redraw for that node, not for the entire widget (a redraw for the
entire widget is only needed when the sizes change, and
_queue_resize() will take care of that),
(do_validate_rows): do not queue a redraw, redraws are only needed
for changes in the visible area and validate_visible_area() takes
care of that,
(gtk_tree_view_row_inserted): for fixed height mode, only queue
a resize and redraw if the node is visible, else no redraw is needed.