Karthus Ghost

Not sure if this is the right thread to post this in, but it does involve the champion...

Is there a reason that Karthus when he dies and becomes a ghost can end up as the top most object? This can be a rather annoying thing. When he becomes a ghost he is untargetable, but other units/objects can end up below him and will also become untargetable. If say a champion is slightly above Karthus and then dies, until they move or you move your camera for a different angle, you can't click on them. I tend to forget as I don't see many people playing Karthus. But when I play ADC and they have a kathus, I notice and it gets quite annoying. .

-Teturact