IOrderGenerator can produce multiple orders (or none)

OpenRa.Game/Controller.cs

@@ -59,10 +59,8 @@ namespace OpenRa.Game
 
 			if( mi.Button == MouseButtons.Right && mi.Event == MouseInputEvent.Down )
 				if( orderGenerator != null )
-				{
+					foreach( var order in orderGenerator.Order( game, new int2( (int)xy.X, (int)xy.Y ) ) )
-					var order = orderGenerator.Order(game, new int2((int)xy.X, (int)xy.Y));
+						order.Apply( game );
-					if (order != null) order.Apply(game);
-				}
 		}
 
         public Unit FindUnit(float2 a, float2 b)

OpenRa.Game/IOrderGenerator.cs

@@ -6,7 +6,7 @@ namespace OpenRa.Game
 {
 	interface IOrderGenerator
 	{
-		Order Order( Game game, int2 xy );
+		IEnumerable<Order> Order( Game game, int2 xy );
 		void PrepareOverlay( Game game, int2 xy );
 	}
 }

OpenRa.Game/Sidebar.cs

@@ -184,10 +184,10 @@ namespace OpenRa.Game
 			Name = name;
 		}
 
-		public Order Order( Game game, int2 xy )
+		public IEnumerable<Order> Order( Game game, int2 xy )
 		{
 			// todo: check that space is free
-			return new PlaceBuildingOrder( this, xy );
+			yield return new PlaceBuildingOrder( this, xy );
 		}
 
 		public void PrepareOverlay(Game game, int2 xy)

OpenRa.Game/Unit.cs

@@ -97,17 +97,17 @@ namespace OpenRa.Game
 			return false;
 		}
 
-		public Order Order( Game game, int2 xy )
+		public IEnumerable<Order> Order( Game game, int2 xy )
 		{
 			if( ( fromCell == toCell || moveFraction == 0 ) && fromCell == xy )
 			{
 				if( SupportsMission( SupportedMissions.Deploy ) )
-					return new DeployMcvOrder( this );
+					yield return new DeployMcvOrder( this );
 				if( SupportsMission( SupportedMissions.Harvest ) )
-					return new HarvestOrder( this );
+					yield return new HarvestOrder( this );
 			}
-			
+			else
-			return new MoveOrder( this, xy );
+				yield return new MoveOrder( this, xy );
 		}
 
 		public void PrepareOverlay(Game game, int2 xy) { }