fixes WEAP roof when selling.

OpenRa.Game/Traits/TraitsInterfaces.cs

@@ -17,7 +17,7 @@ namespace OpenRa.Traits
 	public interface IIssueOrder { Order IssueOrder( Actor self, int2 xy, MouseInput mi, Actor underCursor ); }
 	public interface IResolveOrder { void ResolveOrder(Actor self, Order order); }
 
-	public interface INotifySold { void Sold(Actor self); }
+	public interface INotifySold { void Selling( Actor self );  void Sold( Actor self ); }
 	public interface INotifyDamage { void Damaged(Actor self, AttackInfo e); }
 	public interface INotifyBuildComplete { void BuildingComplete(Actor self); }
 	public interface INotifyProduction { void UnitProduced(Actor self, Actor other); }