widget: mention action_set_enabled in install_action

When looking at `gtk_widget_class_install_action()`, it isn't
immediately obvious how actions can be enabled or disabled. Add a
reference to the `gtk_widget_action_set_enabled()` method so people have
a quick link to that.

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index ac732533ef3d01b031947b72ad8558dbe1647c0a..a88dd0cd14d5b36b6c65e77a932fa07816a8e40a 100644 (file)
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -12598,7 +12598,8 @@ gtk_widget_class_add_action (GtkWidgetClass  *widget_class,
  * actions to be added for all instances of this class.
  *
  * Actions installed by this function are stateless. The only state
- * they have is whether they are enabled or not.
+ * they have is whether they are enabled or not (which can be changed with
+ * [method@Gtk.Widget.action_set_enabled]).
  */
 void
 gtk_widget_class_install_action (GtkWidgetClass              *widget_class,