[gtk+] Fix updating the widget accessible description when using its tooltip

[Matthias Clasen <matthiasc src gnome org>]

commit 69344322d115eed5a79a440a3f951724a1fcaa36
Author: Colomban Wendling <cwendling hypra fr>
Date:   Mon Feb 20 17:39:40 2017 +0100

    Fix updating the widget accessible description when using its tooltip
    
    We need to notify ATK the description changed when the tooltip text associated
    with the widget changes and gtk_widget_accessible_get_description() would use
    it as the description.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779009

 gtk/a11y/gtkwidgetaccessible.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtk/a11y/gtkwidgetaccessible.c b/gtk/a11y/gtkwidgetaccessible.c
index 499976f..2cc5912 100644
--- a/gtk/a11y/gtkwidgetaccessible.c
+++ b/gtk/a11y/gtkwidgetaccessible.c
@@ -479,6 +479,9 @@ gtk_widget_accessible_notify_gtk (GObject    *obj,
     {
       gtk_widget_accessible_update_tooltip (GTK_WIDGET_ACCESSIBLE (atk_obj),
                                             widget);
+
+      if (atk_obj->description == NULL)
+        g_object_notify (G_OBJECT (atk_obj), "accessible-description");
       return;
     }
   else if (g_strcmp0 (pspec->name, "visible") == 0)