[iagno] Add tooltip to undo move button

[Michael Catanzaro <mcatanzaro src gnome org>]

commit a9fa432c780e7d14ca2da7b9c03f264df4c77aea
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Feb 16 10:07:48 2014 -0600

    Add tooltip to undo move button

 src/iagno.vala |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/iagno.vala b/src/iagno.vala
index 71e1deb..7aba64a 100644
--- a/src/iagno.vala
+++ b/src/iagno.vala
@@ -107,6 +107,7 @@ public class Iagno : Gtk.Application
         undo_button.image = image;
         undo_button.valign = Gtk.Align.CENTER;
         undo_button.action_name = "app.undo-move";
+        undo_button.tooltip_text = _("Undo your most recent move");
         undo_button.show ();
 
         headerbar = new Gtk.HeaderBar ();