[gtk+] progress bar: Add CSS documentation

[Matthias Clasen <matthiasc src gnome org>]

commit 479d64e89ac2a1e7b1e6f4f91b31edd8bdaef4cc
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 31 20:30:03 2015 -0400

    progress bar: Add CSS documentation

 gtk/gtkprogressbar.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkprogressbar.c b/gtk/gtkprogressbar.c
index d327120..e8d4987 100644
--- a/gtk/gtkprogressbar.c
+++ b/gtk/gtkprogressbar.c
@@ -65,6 +65,13 @@
  * of the #GtkProgressBar. Functions are provided to control the orientation
  * of the bar, optional text can be displayed along with the bar, and the
  * step size used in activity mode can be set.
+ *
+ * # CSS nodes
+ *
+ * GtkProgressBar has a main CSS node with name progressbar and a subnode
+ * with name progress. The subnode has the style class .pulse when in activity
+ * mode. It gets the style classes .left, .right, .top or .bottom added when
+ * the progress 'touches' the corresponding end of the GtkProgressBar.
  */
 
 #define MIN_HORIZONTAL_BAR_WIDTH   150