[gtk+] treeview: Add a diagram to CSS documentation

[Matthias Clasen <matthiasc src gnome org>]

commit ff4b11226517609e183550b3de2e23e68e194068
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Nov 10 07:36:41 2015 -0500

    treeview: Add a diagram to CSS documentation

 gtk/gtktreeview.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtktreeview.c b/gtk/gtktreeview.c
index 282df7e..8545835 100644
--- a/gtk/gtktreeview.c
+++ b/gtk/gtktreeview.c
@@ -126,9 +126,20 @@
  *
  * # CSS nodes
  *
+ * |[<!-- language="plain" -->
+ * treeview.view
+ * ├── header
+ * │   ├── [column header]
+ * │   ├── [column header]
+   ┊   ┊
+ * │
+ * ╰── [rubberband]
+ * ]|
+ *
  * GtkTreeView has a main CSS node with name treeview and style class .view.
  * It has a subnode with name header, which is the parent for all the column
  * header widgets' CSS nodes.
+ * For rubberband selection, a subnode with name rubberband is used.
  */
 
 enum