[gtk+] flow box: Avoid a critical in keynav

[Matthias Clasen <matthiasc src gnome org>]

commit 692f60ebb0f33d6b0abe1ffbd0a43d212777fbf2
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Aug 26 19:57:15 2015 -0400

    flow box: Avoid a critical in keynav
    
    We were not taking into account that gtk_flow_box_get_next_focusable
    can return NULL, in all callers. Fix that.

 gtk/gtkflowbox.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkflowbox.c b/gtk/gtkflowbox.c
index c19130e..8b65d65 100644
--- a/gtk/gtkflowbox.c
+++ b/gtk/gtkflowbox.c
@@ -3459,7 +3459,7 @@ gtk_flow_box_move_cursor (GtkFlowBox      *box,
               while (!g_sequence_iter_is_end (iter))
                 {
                   iter = gtk_flow_box_get_next_focusable (box, iter);
-                  if (g_sequence_iter_is_end (iter))
+                  if (iter == NULL || g_sequence_iter_is_end (iter))
                     break;
 
                   next = g_sequence_get (iter);