C/GTK+ GTK_IS_PROGESSBAR failed - c

Question

I have a main.c file where a progress bar is created and then it will be updated by other.c file.
Inside the main.c file i have this:
static void
a_func ( GtkWidget *dialog,
struct widget_t *Widget,
gint mode)
{
....
....
Widget->pBar = gtk_progress_bar_new ();
....
....
}
which create and run a dialog. When OK is pushed my_func (Widget); will be called.
Inside the other.c file i have this:
static gboolean
fill (gpointer data)
{
GtkWidget *bar = data;
gtk_progress_bar_pulse (GTK_PROGRESS_BAR (bar));
return TRUE;
}
gint my_func (struct mystruct_t *Widget){
....
....
gtk_progress_bar_pulse (GTK_PROGRESS_BAR (Widget->pBar));
g_timeout_add (100, fill, GTK_PROGRESS_BAR (Widget->pBar));
while (gtk_events_pending ())
gtk_main_iteration ();
....
....
}
The problem is that i'm getting this error:
GLib-GObject-WARNING **: invalid unclassed pointer in cast to 'GtkProgressBar'
Gtk-CRITICAL **: gtk_progress_bar_pulse: assertion 'GTK_IS_PROGRESS_BAR (pbar)' failed
EDIT 1:
This is a compilable example: https://gist.github.com/polslinux/96e7b18176ac66e50ee1
EDIT 2:
This is a simple workflow graph: http://it.tinypic.com/r/316us0y/8

Answer 1

This can not work:
crypt_file (Widget);
gtk_widget_destroy (dialog);
You add a GSource to your mainloop which modifies Widget->pBar but you never remove it. On the other hand you destroy the dialog (and thus also pBar itself as it is part of the widget sub-tree) which in turn renders Widget->pBar useless/makes it a dangling pointer.
Things you did not ask for (excuse the direct approach)
Your variable names are crappy at best, upper lower case, calling things Widget which are no widgets but mere structs.
Make sure you do not split into callbacks and other C functions. That will end up totally messy as your project grows.
Try to go for object-orientation. Create a GObject derived klass which handles the mess internally instead of passing translucent structs around.