def on_about_menu_item_activate(self, menuitem, data=None):
''' Called when the user clicks the 'About' menu. We create a GtkAboutDialog.
This dialog will NOT be modal but will be on top of the main application window.'''
if self.about_dialog:
self.about_dialog.present()
return
about_dialog=AboutDialog(self)
self.about_dialog = about_dialog
about_dialog.show()
