[iagno] Use headerbar in the preferences dialog

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 1caeb1518eb10812c8c526931e944b0fd442cd8c
Author: Yosef Or Boczko <yoseforb src gnome org>
Date:   Tue Mar 25 23:58:51 2014 +0200

    Use headerbar in the preferences dialog
    
    https://bugzilla.gnome.org/show_bug.cgi?id=727051

 src/iagno.vala |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/src/iagno.vala b/src/iagno.vala
index fe5b076..f8571a8 100644
--- a/src/iagno.vala
+++ b/src/iagno.vala
@@ -493,8 +493,7 @@ public class Iagno : Gtk.Application
     {
         var propbox = new Gtk.Dialog.with_buttons (_("Iagno Preferences"),
                                                    window,
-                                                   0,
-                                                   _("_Close"), Gtk.ResponseType.CLOSE,
+                                                   Gtk.DialogFlags.USE_HEADER_BAR,
                                                    null);
 
         propbox.set_border_width (5);