[libchamplain] launcher-gtk: Fix type warning

[Pierre-Luc Beaudoin <plbeaudoin src gnome org>]

commit 1defd555c54b130f6f5cef67d24c8e7983999c4a
Author: Simon Wenner <simon wenner ch>
Date:   Mon Jul 13 02:16:38 2009 +0200

    launcher-gtk: Fix type warning

 demos/launcher-gtk.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/demos/launcher-gtk.c b/demos/launcher-gtk.c
index 83bcf8c..23cdf1f 100644
--- a/demos/launcher-gtk.c
+++ b/demos/launcher-gtk.c
@@ -275,7 +275,8 @@ main (int argc,
   gtk_container_add (GTK_CONTAINER (bbox), button);
 
   button = gtk_spin_button_new_with_range(0, 20, 1);
-  gtk_spin_button_set_value (button, champlain_view_get_zoom_level (view));
+  gtk_spin_button_set_value (GTK_SPIN_BUTTON (button),
+      champlain_view_get_zoom_level (view));
   g_signal_connect (button, "changed", G_CALLBACK (zoom_changed), view);
   g_signal_connect (view, "notify::zoom-level", G_CALLBACK (map_zoom_changed),
       button);