[gtk+] Improve GtkStack documentation

[Matthias Clasen <matthiasc src gnome org>]

commit 8195244e3bb1c53204e5a4d18b249634e713b2fa
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Mar 6 22:50:40 2014 -0500

    Improve GtkStack documentation
    
    As has been pointed out in
    https://bugzilla.gnome.org/show_bug.cgi?id=725711
    it is a little confusing that we have the concept of
    a visible child and of the child being visible itself.

 gtk/gtkstack.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index 6d3a57a..3b338be 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -1392,6 +1392,10 @@ gtk_stack_get_visible_child_name (GtkStack *stack)
  * two will be animated with the current
  * transition type of @stack.
  *
+ * Note that the @child widget has to be visible itself
+ * (see gtk_widget_show()) in order to become the visible
+ * child of @stack.
+ *
  * Since: 3.10
  */
 void
@@ -1430,6 +1434,10 @@ gtk_stack_set_visible_child (GtkStack  *stack,
  * two will be animated with the current
  * transition type of @stack.
  *
+ * Note that the child widget has to be visible itself
+ * (see gtk_widget_show()) in order to become the visible
+ * child of @stack.
+ *
  * Since: 3.10
  */
 void
@@ -1449,6 +1457,10 @@ gtk_stack_set_visible_child_name (GtkStack   *stack,
  *
  * Makes the child with the given name visible.
  *
+ * Note that the child widget has to be visible itself
+ * (see gtk_widget_show()) in order to become the visible
+ * child of @stack.
+ *
  * Since: 3.10
  */
 void