Comment 6 for bug 127531

The fix is still not in trunk. The solution by Jean-Francois works for me (I actually implemented the exact same solution before searching bug reports so yay for my newbie debug skills).

In the GtkProgressBarStack class in ui.py:
current:
    def remove(self, pb):
        self.vbox.remove(pb)

fix:
    def remove(self, pb):
        self.vbox.remove(pb)
        if len(self.vbox.get_children()) == 0:
            self.destroy()