Since i switched to AssistUO, i haven't had that grey issue anymore.
In AUO there's a 'friends' list option. It allows you to add 'friends' to the list (being pets, or players) that you can keep healed, even to a desireable level (50%, 60% etc).
It burns through bandages, but it works. I haven't had the panic attacks no more and freezing cause all my pets are taking damage and WHICH ONE DO I NEED TO HEAL FIRST!! lol
i can highly recommend it!
Moris