I send you the thread code. There is only this thread calling gtk, and for now no interactions between this thread the others parts of the program. serveur_t *controle; void *envoi_ordre(void *arg){ GtkWidget *window1; gtk_init(NULL, NULL); /* interface designed with glade... */ /* * The following code was added by Glade to create one of each component * (except popup menus), just so that you see something after building * the project. Delete any components that you don't want shown initially. */ controle=(serveur_t *)arg; window1 = create_window1 (); gtk_widget_show (window1); gtk_main (); return ; }