[gnome-calendar] build: fixed warning

[Erick Pérez Castellanos <erickpc src gnome org>]

commit 34aa3d39228c0424a99f134d6ce1098237c39819
Author: Erick Pérez Castellanos <erick red gmail com>
Date:   Thu May 30 17:05:59 2013 -0400

    build: fixed warning

 src/gcal-nav-bar.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/gcal-nav-bar.c b/src/gcal-nav-bar.c
index 78fb026..49aebc1 100644
--- a/src/gcal-nav-bar.c
+++ b/src/gcal-nav-bar.c
@@ -189,7 +189,7 @@ gcal_nav_bar_btn_clicked (GtkButton *button,
   GcalNavBarPrivate *priv;
   priv = GCAL_NAV_BAR (user_data)->priv;
 
-  if (button == priv->back_button)
+  if ((GtkWidget*) button == priv->back_button)
     g_signal_emit (GCAL_NAV_BAR (user_data), signals[MOVE], 0, FALSE);
   else
     g_signal_emit (GCAL_NAV_BAR (user_data), signals[MOVE], 0, TRUE);