internal abstract void DeclineBuddy(InstantMessageBuddy buddy);
internal virtual void UnblockBuddy(InstantMessageBuddy buddy) { throw new NotImplementedException(); }
internal abstract void AcceptBuddy(InstantMessageBuddy buddy, InstantMessageGroup group);
internal abstract void CopyBuddy(InstantMessageGroup group, InstantMessageBuddy buddy);
internal abstract void MoveBuddy(InstantMessageGroup oldGroup, InstantMessageGroup newGroup, InstantMessageBuddy buddy);
internal abstract void RemoveFromGroup(InstantMessageGroup group, InstantMessageBuddy buddy);
internal abstract void RemoveBuddy(InstantMessageBuddy buddy);