[gtk+] stack switcher: Clarify CSS documentation

[Matthias Clasen <matthiasc src gnome org>]

commit c59ef7bf2fb9e496f051d6a69a1bbb5d4ac34c77
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Nov 5 08:17:49 2015 -0500

    stack switcher: Clarify CSS documentation

 gtk/gtkstackswitcher.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkstackswitcher.c b/gtk/gtkstackswitcher.c
index 32b643e..226ec9e 100644
--- a/gtk/gtkstackswitcher.c
+++ b/gtk/gtkstackswitcher.c
@@ -45,7 +45,12 @@
  *
  * # CSS nodes
  *
- * GtkStackSwitcher has a single CSS node names stackswitcher.
+ * GtkStackSwitcher has a single CSS node names stackswitcher and
+ * style class .sidebar.
+ *
+ * When circumstances require it, GtkStackSwitcher adds the
+ * .needs-attention style class to the widgets representing the
+ * stack pages.
  */
 
 typedef struct _GtkStackSwitcherPrivate GtkStackSwitcherPrivate;