Comment 13 for bug 1058652

@Victor: I can confirm that this bug was fixed in your code.

I myself have also spent some time investigating this problem, it was because the `menuhash` in Panel.vala maps from strings (indicators' name) to Gtk.MenuEntry objects, expecting that each indicator only has one indicator button. Therefore, when an app indicator is removed, the last added app indicator is removed as well (not necessarily the one right next to it).