Aggiunta gestione del clic su X nella finestra di progresso

diff --git a/DrPrintGui/Dialogs.py b/DrPrintGui/Dialogs.py
index d6b4787..70f17b1 100644
--- a/DrPrintGui/Dialogs.py
+++ b/DrPrintGui/Dialogs.py
@@ -104,6 +104,8 @@ class ProgressDialog(gtk.Dialog):

         cancel_button.connect("clicked", self.cancel)

+        self.connect("destroy", self.cancel)
+
     def cancel(self, widget):
         self.emit('transfer-cancelled')
         self.hide()