The base class OnlineUnlockStatus has a pure virtual function void saveState (const String&).
I think it would be quite a common implementation to write something to a file in this override. The File class and the FileOutputStream class return either bools or Results to indicate success or failure. However, saveState returns void to its caller, OnlineUnlockStatus::save(), which in turn also returns void.
So I think in order to get the error back up to the call to OnlineUnlockStatus::save() in the GUI, I would need to use an exception. Would it be a good improvement to have OnlineUnlockStatus::save() and OnlineUnlockStatus::saveState() return Results?