GTK app to change pic on click

["Midhun A" <midhunagni gmail com>]

Hi All,

  I am very new to GTK+ (started out yesterday). I am writing a simple
application which will show pictures one by one on button click.
Although I am able to get my first picture, the picture does not
change on click of the button (next or previous). The full code is as
below.

#include <stdio.h>
#include <gtk/gtk.h>
#include <string.h>
#include <unistd.h>
#include </usr/include/stdio.h>
#include <glib.h>

GtkWidget *image2;
GtkWidget *window;
GtkWidget *vbox;
GtkWidget *prev_button, *next_button;



gchar *files[6] =
{
"/home/pics/1.jpg",
"/home/pics/2.jpg",
"/home/pics/3.jpg",
"/home/pics/4.jpg",
"/home/pics/5.jpg",
"/home/pics/6.jpg"
};

typedef struct{
gint data;
} data;

void prev_callback (GtkWidget *widget, data *v )
{
	gint cnt = v->data;
	if (cnt == 0)
		cnt = 5;	
	else
		cnt = cnt - 1;
			
	image2 = gtk_image_new_from_file (files[cnt]);
}

void next_callback (GtkWidget *widget, data *v)
{
	int cnt = v->data;
	if (cnt == 5)
		cnt = 0;	
	else
		cnt = cnt + 1;
			
	image2 = gtk_image_new_from_file (files[cnt]);
}


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

	data *w = g_slice_new(data);
	w->data = 0;

	gtk_init(&argc,&argv);
	window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
	gtk_window_maximize (window);
	
	vbox = gtk_vbox_new(FALSE, 1);

	image2 = gtk_image_new_from_file (files[w->data]);
	gtk_container_add(GTK_CONTAINER(vbox), image2);
				
	prev_button = gtk_button_new_with_mnemonic ("Previous");
	next_button = gtk_button_new_with_mnemonic ("Next");

	gtk_widget_set_name(prev_button,"prev_button");
	gtk_widget_set_name(next_button,"next_button");	

	gtk_container_add(GTK_CONTAINER(vbox), prev_button);
	gtk_container_add(GTK_CONTAINER(vbox), next_button);		
	gtk_container_add(GTK_CONTAINER(window), vbox);	

	g_signal_connect (G_OBJECT (prev_button), "clicked", G_CALLBACK
(prev_callback),(gpointer)w);
	g_signal_connect (G_OBJECT (next_button), "clicked", G_CALLBACK
(next_callback),(gpointer)w);

	gtk_widget_show (image2);
	gtk_widget_show (prev_button);
	gtk_widget_show (next_button);		
	gtk_widget_show (vbox);	
	gtk_widget_show (window);
	
	gtk_main();
	return 0;
}


This is very primitive code to test the functionality.  Whats wrong
with the code? I would like to see the previous picture on click of
previous button and the next picture on click of next button.


Any help would be appreciated,
Thanks,
Midhun.