based on reports and patches by Iñaki García Etxebarria:
https://bugzilla.gnome.org/show_bug.cgi?id=781246
https://bugzilla.gnome.org/show_bug.cgi?id=785423
* no child widget. The returned widget does not have a reference
* added, so you do not need to unref it.
*
- * Returns: (transfer none): pointer to child of the #GtkBin
+ * Returns: (transfer none) (nullable): the child of @bin, or %NULL if it does
+ * not have a child.
**/
GtkWidget*
gtk_bin_get_child (GtkBin *bin)
* gtk_widget_get_parent_window:
* @widget: a #GtkWidget.
*
- * Gets @widget’s parent window.
+ * Gets @widget’s parent window, or %NULL if it does not have one.
*
- * Returns: (transfer none): the parent window of @widget.
+ * Returns: (transfer none) (nullable): the parent window of @widget, or %NULL
+ * if it does not have a parent window.
**/
GdkWindow *
gtk_widget_get_parent_window (GtkWidget *widget)