[gtk+] Add some more missing nullable annotations

[Timm Bäder <baedert src gnome org>]

commit a28103cf51459559e4c22ae2d2843edaa94e5ba0
Author: Timm Bäder <mail baedert org>
Date:   Tue Dec 1 13:40:46 2015 +0100

    Add some more missing nullable annotations

 gtk/gtkgrid.c    |    2 +-
 gtk/gtklistbox.c |    4 ++--
 gtk/gtkwindow.c  |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkgrid.c b/gtk/gtkgrid.c
index 880247f..6ba8c0c 100644
--- a/gtk/gtkgrid.c
+++ b/gtk/gtkgrid.c
@@ -1951,7 +1951,7 @@ gtk_grid_attach_next_to (GtkGrid         *grid,
  * Gets the child of @grid whose area covers the grid
  * cell whose upper left corner is at @left, @top.
  *
- * Returns: (transfer none): the child at the given position, or %NULL
+ * Returns: (transfer none) (nullable): the child at the given position, or %NULL
  *
  * Since: 3.2
  */
diff --git a/gtk/gtklistbox.c b/gtk/gtklistbox.c
index f9b74b7..6a875bf 100644
--- a/gtk/gtklistbox.c
+++ b/gtk/gtklistbox.c
@@ -653,7 +653,7 @@ gtk_list_box_get_selected_row (GtkListBox *box)
  * If @_index is negative or larger than the number of items in the
  * list, %NULL is returned.
  *
- * Returns: (transfer none): the child #GtkWidget or %NULL
+ * Returns: (transfer none) (nullable): the child #GtkWidget or %NULL
  *
  * Since: 3.10
  */
@@ -3332,7 +3332,7 @@ gtk_list_box_row_changed (GtkListBoxRow *row)
  * in a #GtkListBoxUpdateHeaderFunc to see if there is a header
  * set already, and if so to update the state of it.
  *
- * Returns: (transfer none): the current header, or %NULL if none
+ * Returns: (transfer none) (nullable): the current header, or %NULL if none
  *
  * Since: 3.10
  */
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 4be1034..849ff8c 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -1118,7 +1118,7 @@ gtk_window_class_init (GtkWindowClass *klass)
   /**
    * GtkWindow:set-focus:
    * @window: the window which received the signal
-   * @widget: the newly focused widget (or %NULL for no focus)
+   * @widget: (nullable): the newly focused widget (or %NULL for no focus)
    *
    * This signal is emitted whenever the currently focused widget in
    * this window changes.