[gtk] widget: Clarify docs for action inheritance

[Matthias Clasen <matthiasc src gnome org>]

commit 203d612afd78d577cb3ae544763824771d049c97
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jun 22 19:17:30 2019 -0400

    widget: Clarify docs for action inheritance
    
    Spell out how action inheritance works wrt to prefixes.

 gtk/gtkwidget.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 944cf85d18..045dcef9d7 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -11928,11 +11928,15 @@ _gtk_widget_get_action_muxer (GtkWidget *widget,
  *
  * Inserts @group into @widget. Children of @widget that implement
  * #GtkActionable can then be associated with actions in @group by
- * setting their “action-name” to
- * @prefix.`action-name`.
+ * setting their “action-name” to @prefix.`action-name`.
  *
- * If @group is %NULL, a previously inserted group for @name is removed
- * from @widget.
+ * Note that inheritance is defined for individual actions. I.e.
+ * even if you insert a group with prefix @prefix, actions with
+ * the same prefix will still be inherited from the parent, unless
+ * the group contains an action with the same name.
+ *
+ * If @group is %NULL, a previously inserted group for @name is
+ * removed from @widget.
  */
 void
 gtk_widget_insert_action_group (GtkWidget    *widget,