请教GTK！

qiqixiao

   
     创建了一个窗口，用set_title设置了标题为：“HELLO！”，然后添加了一个按钮，请问当点击按钮后，如何改变此窗体的title？（比如title改为“HI！”）
>;
>; 我水平不高，没能实现，请看我的代码，麻烦高手帮我修改一下！

#include <gtk/gtk.h>;

GtkWidget *window;

void set_title ( GtkWidget *widget, GdkEvent *event, gpointer data )
{

/* window = gtk_window_new (GTK_WINDOW_TOPLEVEL);*/

gtk_window_set_title (GTK_WINDOW (window), "HI!";

/* window = gtk_window_new (GTK_WINDOW_TOPLEVEL);*/

gtk_widget_show (window);
}

gint delete_event (GtkWidget *widget, GdkEvent *event, gpointer data)
{
return FALSE;

}

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


int main( int argc, char *argv[] )
{
/* GtkWidget *window;*/
GtkWidget *button;
GtkWidget *box1;

gtk_init(&argc, &argv);

/*建立窗体*/
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Hello!";
g_signal_connect (G_OBJECT (window), "delete_event", G_CALLBACK (delete_event), NULL);
g_signal_connect (G_OBJECT (window), "destroy",G_CALLBACK (destroy), NULL);
gtk_widget_set_size_request (window, 300, 100);

/*建立组装盒*/
box1 = gtk_vbox_new (TRUE, 0);
gtk_container_add (GTK_CONTAINER (window), box1);

/*建立“Input”按纽*/
button = gtk_button_new_with_label ("Input";
/* g_signal_connect (G_OBJECT (button), "clicked", G_CALLBACK (callback), "Input";*/
gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0);
gtk_widget_show (button);

/*建立“ChangeTitle”按钮*/
button = gtk_button_new_with_label ("ChangeTitle";
g_signal_connect (G_OBJECT (button), "clicked", G_CALLBACK (gtk_window_set_title), "ChangeTitle";
gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0);
gtk_widget_show (button);
/*建立“Quit”按钮*/
button = gtk_button_new_with_label ("Quit";
g_signal_connect_swapped (G_OBJECT (button), "clicked", G_CALLBACK (gtk_widget_destroy), window);
gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0);
gtk_widget_show (button);

gtk_widget_show (box1);
gtk_widget_show (window);
gtk_main();
return 0;

}

请教：
代码虽然编译通过，但是“ChangTitle”的功能没实现，并且每点击一次“ChangeTitle”，终端就输出一条信息 ，如下：

GTK-CRITICAL**：file gtkwindow.c: line 953 (gtk_window_set_title) : assertion `GTK_IS_WINDOW (window)` failed