[gtk+] GtkStack: Add some missing nullable annotations

[Timm Bäder <baedert src gnome org>]

commit f154875e08bbd9c93d73887113638c72923d09fd
Author: Timm Bäder <mail baedert org>
Date:   Tue Nov 24 09:44:08 2015 +0100

    GtkStack: Add some missing nullable annotations

 gtk/gtkstack.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index a817b0b..bc9e347 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -1339,7 +1339,7 @@ gtk_stack_remove (GtkContainer *container,
  * the argument. Returns %NULL if there is no child with this
  * name.
  *
- * Returns: (transfer none): the requested child of the #GtkStack
+ * Returns: (transfer none) (nullable): the requested child of the #GtkStack
  *
  * Since: 3.12
  */
@@ -1720,7 +1720,7 @@ gtk_stack_get_interpolate_size (GtkStack *stack)
  * Gets the currently visible child of @stack, or %NULL if
  * there are no visible children.
  *
- * Returns: (transfer none): the visible child of the #GtkStack
+ * Returns: (transfer none) (nullable): the visible child of the #GtkStack
  *
  * Since: 3.10
  */
@@ -1741,7 +1741,7 @@ gtk_stack_get_visible_child (GtkStack *stack)
  * Returns the name of the currently visible child of @stack, or
  * %NULL if there is no visible child.
  *
- * Returns: (transfer none): the name of the visible child of the #GtkStack
+ * Returns: (transfer none) (nullable): the name of the visible child of the #GtkStack
  *
  * Since: 3.10
  */