File classic_treeview__alternating_row_colours.patch of Package gtk3

# GtkTreeView:  Add style classes to assist zebra striping
#
# A lot of users like the alternating row colors that many GTK+ 2 theme
# engines could and did draw; the alternating row colors enabled users
# to quickly find their way across a long list without getting lost or
# confused.  These alternating color patterns are known as "zebra stripes".
#
# Due to slow but steady code rot in the GtkTreeView source code, the
# mechanism to implement zebra striping was eventually removed, whether
# accidentally or intentionally.  This patch adds style classes to each
# tree view cell to indicate whether the cell is on an odd or even row,
# and whether the column that contains the cell is the column that is
# used to sort the tree view.  These style classes allow themes to choose
# appropriate background colors for each cell based on its position, rather
# than forcing the theme designer to color all cells the same.
#
# An example of zebra striping in action:
#
#   .caja-notebook treeview.even:not(:selected)
#   {
#     background-color: shade(@theme_base_color, .9);
#   }
#
#   .caja-notebook treeview.sorted.odd:not(:selected)
#   {
#     background-color: shade(@theme_base_color, .9);
#   }
#
#   .caja-notebook treeview.sorted.even:not(:selected)
#   {
#     background-color: shade(@theme_base_color, .81);
#   }

diff -uprN gtk+-3.24.30-original/gtk/gtktreeview.c gtk+-3.24.30-patched/gtk/gtktreeview.c
--- gtk+-3.24.30-original/gtk/gtktreeview.c	2021-06-15 16:58:25.000000000 -0400
+++ gtk+-3.24.30-patched/gtk/gtktreeview.c	2021-12-24 02:06:17.136272294 -0500
@@ -5302,6 +5302,18 @@ gtk_tree_view_bin_draw (GtkWidget      *
 
           gtk_style_context_add_class (context, GTK_STYLE_CLASS_CELL);

+    if (list == first_column)
+      gtk_style_context_add_class (context, rtl ? "last" : "first");
+    if (list == last_column)
+      gtk_style_context_add_class (context, rtl ? "first" : "last"); 
+    if (_gtk_rbtree_node_get_index (tree, node) % 2 == 0)
+      gtk_style_context_add_class (context, "odd");
+    else
+      gtk_style_context_add_class (context, "even");
+
+    if (flags & GTK_CELL_RENDERER_SORTED)
+      gtk_style_context_add_class (context, "sorted");
+
 	  if (node == tree_view->priv->cursor_node && has_can_focus_cell
               && ((column == tree_view->priv->focus_column
                    && tree_view->priv->draw_keyfocus &&