[gtk+] ListBox: Update docs of GtkListBoxUpdateHeaderFunc

[Alexander Larsson <alexl src gnome org>]

commit e6ac9b08621a75a5f16383ab3f6a3ff5c9e3da37
Author: Timm Bäder <mail baedert org>
Date:   Mon Sep 16 20:08:35 2013 +0200

    ListBox: Update docs of GtkListBoxUpdateHeaderFunc
    
    before is always NULL for the first row.

 gtk/gtklistbox.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtklistbox.h b/gtk/gtklistbox.h
index 8d425ff..1ca5ece 100644
--- a/gtk/gtklistbox.h
+++ b/gtk/gtklistbox.h
@@ -130,7 +130,7 @@ typedef gint (*GtkListBoxSortFunc) (GtkListBoxRow *row1,
 /**
  * GtkListBoxUpdateHeaderFunc:
  * @row: the row to update
- * @before: the row before @row, or %NULL if it is first
+ * @before: (allow-none): the row before @row, or %NULL if it is first
  * @user_data: (closure): user data
  *
  * Whenever @row changes or which row is before @row changes this