Comment 9 for bug 868995

Checking if the wait dialog is active before hiding it (self._wait.is_active()) mitigates the symptoms slightly - but causes a different problem where the dialog won't get hidden because Gtk says it's not active when it is actually being displayed.

It's been suggested that the fact that the main Checkbox 'window' is in fact a GtkDialog and the wait dialog is a GtkWindow could be confusing the window manager. However changing this around seems to require quite a significant amount of refactoring. It's something we could try with the Checkbox UI re-write, but it won't happen in a short period of time.