Gtk-ERROR **: Incompatible build!

["John Zoidberg" <zohn joidberg gmail com>]

I get the following error when trying to compile&run a GTK+ app in Devcpp
under Windows XP:

Gtk-ERROR **: Incompatible build!
The code using GTK+ thinks GtkBox is of different
size than it actually is in this build of GTK+.
On Windows, this probably means that you have compiled
your code with gcc without the -mms-bitfields switch,
or that you are using an unsupported compiler.
aborting...

It happens with the default "create a new GTK+ project" code, which looks
like this:

#include <gtk/gtk.h>

static void destroy( GtkWidget *widget,
                    gpointer   data );

int main( int   argc,
         char *argv[] )
{
   GtkWidget *window;

   gtk_init (&argc, &argv);

   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

   g_signal_connect (G_OBJECT (window), "destroy",
             G_CALLBACK (destroy), NULL);

/*  TODO: type some code */

   gtk_widget_show  (window);

   gtk_main ();

   return 0;
}

static void destroy( GtkWidget *widget,
                    gpointer   data )
{
   gtk_main_quit ();
}

When I go into project options, the "-mms-bitfields" switch is there.