[gtk+] model button: Add diagrams to the CSS node documentation

[Matthias Clasen <matthiasc src gnome org>]

commit 09f7c8511bf9dd6d597411d922b11c0a1c429ed9
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Nov 3 12:51:52 2015 -0500

    model button: Add diagrams to the CSS node documentation

 gtk/gtkmodelbutton.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmodelbutton.c b/gtk/gtkmodelbutton.c
index e65cc80..1c60e4b 100644
--- a/gtk/gtkmodelbutton.c
+++ b/gtk/gtkmodelbutton.c
@@ -105,6 +105,33 @@
  *   </child>
  * </object>
  * ]|
+ *
+ * # CSS nodes
+ *
+ * |[<!-- language="plain" -->
+ * modelbutton
+ * ├── ...
+ * ╰── check
+ * ]|
+ *
+ * |[<!-- language="plain" -->
+ * modelbutton
+ * ├── ...
+ * ╰── radio
+ * ]|
+ *
+ * |[<!-- language="plain" -->
+ * modelbutton
+ * ├── ...
+ * ╰── arrow
+ * ]|
+ *
+ * GtkModelButton has a main CSS node with name modelbutton, and a subnode,
+ * which will have the name check, radio or arrow, depending on the role
+ * of the button and whether it has a menu name set.
+ *
+ * The subnode is positioned before or after the content nodes and gets the
+ * .left or .right style class, depending on where it is located.
  */
 
 struct _GtkModelButton