[gtk+] Add nullable return annotation to gtk_notebook_get_tab_label

[Matthias Clasen <matthiasc src gnome org>]

commit 59a22b3d7e63d9838139163629499b1ee33f524d
Author: Iñaki García Etxebarria <garetxe gmail com>
Date:   Sat Apr 29 13:08:26 2017 +0200

    Add nullable return annotation to gtk_notebook_get_tab_label
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781935

 gtk/gtknotebook.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtknotebook.c b/gtk/gtknotebook.c
index 94d62a4..e9223e0 100644
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -6916,7 +6916,7 @@ gtk_notebook_popup_disable (GtkNotebook *notebook)
  * %NULL is returned if @child is not in @notebook or
  * if no tab label has specifically been set for @child.
  *
- * Returns: (transfer none): the tab label
+ * Returns: (transfer none) (nullable): the tab label
  */
 GtkWidget *
 gtk_notebook_get_tab_label (GtkNotebook *notebook,