Enforce required owner in map editor

It can easily happen that mappers forget to set the current player to Neutral before placing more trees, for example, so we force the editor to set a valid owner in such cases.

OpenRA.Mods.Common/EditorBrushes/EditorActorBrush.cs

@@ -41,6 +41,7 @@ public EditorActorBrush(EditorViewportControllerWidget editorWidget, ActorInfo a
 
 			Actor = actor;
 			this.owner = owner;
+			var ownerName = owner.Name;
 
 			preview = editorWidget.Get<ActorPreviewWidget>("DRAG_ACTOR_PREVIEW");
 			preview.GetScale = () => worldRenderer.Viewport.Zoom;
@@ -50,10 +51,15 @@ public EditorActorBrush(EditorViewportControllerWidget editorWidget, ActorInfo a
 			if (buildingInfo != null)
 				centerOffset = buildingInfo.CenterOffset(world);
 
+			// Enforce Neutral or Creeps owner if the actor has RequiresSpecificOwner
+			var specificOwnerInfo = actor.TraitInfoOrDefault<RequiresSpecificOwnerInfo>();
+			if (specificOwnerInfo != null && !specificOwnerInfo.ValidOwnerTypes.Contains(ownerName))
+				ownerName = specificOwnerInfo.ValidOwnerTypes.First();
+
 			var td = new TypeDictionary();
 			td.Add(new FacingInit(facing));
 			td.Add(new TurretFacingInit(facing));
-			td.Add(new OwnerInit(owner.Name));
+			td.Add(new OwnerInit(ownerName));
 			td.Add(new FactionInit(owner.Faction));
 			preview.SetPreview(actor, td);
 
@@ -94,8 +100,14 @@ public bool HandleMouseInput(MouseInput mi)
 				if (!footprint.All(c => world.Map.Tiles.Contains(cell + c)))
 					return true;
 
+				// Enforce Neutral or Creeps owner if the actor has RequiresSpecificOwner
+				var ownerName = owner.Name;
+				var specificOwnerInfo = Actor.TraitInfoOrDefault<RequiresSpecificOwnerInfo>();
+				if (specificOwnerInfo != null && !specificOwnerInfo.ValidOwnerTypes.Contains(ownerName))
+					ownerName = specificOwnerInfo.ValidOwnerTypes.First();
+
 				var newActorReference = new ActorReference(Actor.Name);
-				newActorReference.Add(new OwnerInit(owner.Name));
+				newActorReference.Add(new OwnerInit(ownerName));
 
 				newActorReference.Add(new LocationInit(cell));