#include <stdio.h>
#include <gdk/gdkx.h>
#include <gtk/gtk.h>

int 
main(int argc, char *argv[]) 
{
   GtkWidget *win = NULL;
   GtkWidget *img = NULL;
   GdkBitmap *mask;

   gtk_init(&argc, &argv);

   win = gtk_window_new(GTK_WINDOW_TOPLEVEL);

   img = gtk_image_new_from_file("bg.png");
   gdk_pixbuf_render_pixmap_and_mask(gtk_image_get_pixbuf(GTK_IMAGE(img)), 
                                     NULL, &mask, 255);
   gtk_widget_shape_combine_mask(win, mask, 0, 0);

   gtk_window_set_decorated(GTK_WINDOW(win), FALSE);
   gtk_widget_show_all(win);

   gtk_main();
   return 0;
}