[glade--]Question from newbie

Hi all,

I am self-learning gtk programming at the moment and I have struck a
problem.

I am having problem closing the application down. I tried calling 
Gtk::Main::quit() in a button's callback, gcc complained..

  c++ -DHAVE_CONFIG_H -I. -I. -I..     -g -O2 -I/usr/lib/gtkmm/include 
-I/usr/lib/gnomemm/include -I/usr/include -DNEED_GNOMESUPPORT_H 
-I/usr/lib/gnome-libs/include -I/usr/lib/glib/include 
-I/usr/X11R6/include -I/usr/lib/sigc++/include -I/usr/include/gtk-1.2 
-I/usr/include/glib-1.2 -c WN_Test1.cc
WN_Test1.cc: In method `void WN_Test1::on_BT_Close_clicked ()':
WN_Test1.cc:13: no method `Gtk::Main::quit'
make: *** [WN_Test1.o] Error 1

How do I close down my application ??

Thanks.
Alex