#include <gtk/gtk.h>

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

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "Main Window");
    gtk_window_set_default_size(GTK_WINDOW(window), 230, 150);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);

    fixed = gtk_fixed_new();
    gtk_container_add(GTK_CONTAINER(window), fixed);

    toplevel = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(toplevel), "Any Top Level Window");
    gtk_window_set_default_size(GTK_WINDOW(toplevel), 230, 150);
    gtk_window_set_position(GTK_WINDOW(toplevel), GTK_WIN_POS_CENTER);

    gtk_widget_show_all(window);

    gtk_fixed_put(GTK_FIXED(fixed), toplevel, 0, 0); // GTK GPF happend here
    gtk_main();

    return 0;
}
