Update multiple progress bar with gtk c++ - c

Question

I need to output the i progress bars and update them all. But only the last one updates i times. This is the code:
static void calculaPi (GtkButton * boton, Datos * dDatos){
const char * threads;
GtkWidget * barra, *bot2, *button, *progress, *vbox;
threads = gtk_entry_get_text(GTK_ENTRY(dDatos->dthreads ));
gint ithreads = 1;
ithreads = atoi(threads);
barra = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title((GtkWindow *) barra, "Loteria de Threads");
gtk_window_set_default_size(GTK_WINDOW(barra), 300, ithreads*30);
gtk_window_set_position(GTK_WINDOW(barra), GTK_WIN_POS_CENTER);
button = gtk_button_new_with_label ("Click me!");
vbox = gtk_vbox_new (FALSE, 5);
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 5);
gtk_container_add (GTK_CONTAINER (barra), vbox);
for (gint i = 1 ; i <= ithreads; i++) {
progress = gtk_progress_bar_new ();
gtk_box_pack_start (GTK_BOX (vbox), progress, FALSE, FALSE, 5);
g_object_set_data (G_OBJECT (barra), "pbar", (gpointer) progress);
g_signal_connect (G_OBJECT (button), "clicked",
G_CALLBACK (button_clicked), (gpointer) barra);
}
bot2 = gtk_button_new_with_label("Salir");
gtk_box_pack_start (GTK_BOX (vbox), bot2, FALSE, FALSE, 5);
gtk_widget_set_size_request(bot2, 100, 35);
g_signal_connect (G_OBJECT (bot2), "clicked",
G_CALLBACK (destroy),
G_OBJECT (barra));
gtk_widget_show_all(barra);
gtk_main();
}
static void
button_clicked (GtkButton *button,
GtkWidget *barra)
{
GtkProgressBar *progress;
gdouble percent = 0.0;
gtk_widget_set_sensitive (GTK_WIDGET (button), FALSE);
progress = GTK_PROGRESS_BAR (g_object_get_data (G_OBJECT (barra), "pbar"));
while (percent <= 100.0)
{
gchar *message = g_strdup_printf ("%.0f%% Complete", percent);
gtk_progress_bar_set_fraction (progress, percent / 100.0);
gtk_progress_bar_set_text (progress, message);
while (gtk_events_pending ())
gtk_main_iteration ();
g_usleep (500000);
percent += 5.0;
}
}

Answer 1

With this line:
g_object_set_data (G_OBJECT (barra), "pbar", (gpointer) progress);
you override previous value of "pbar" data entry on each loop iteration. When you later retrive it in button_clicked() you get the last set value, i.e. the last progress bar.
In this particular case you can just pass progress widget as user data (and drop g_object_[gs]et_data() calls) for button_clicked() callback: the function doesn't use current barra window for anything else anyway.
In a more general way, you should learn how to use your own structures for user data parameters. A common way is to declare and use one structure for given toplevel type and store pointers to widgets you need to access from callbacks in it.