diff --git a/OpenRa.Game/Harvester.cs b/OpenRa.Game/Harvester.cs
index 860fe6d7b0..67e46d22d4 100644
--- a/OpenRa.Game/Harvester.cs
+++ b/OpenRa.Game/Harvester.cs
@@ -11,11 +11,11 @@ namespace OpenRa.Game
 		{
 		}
 
-		public override IOrder Order( int2 xy )
+		public override IOrder Order( Game game, int2 xy )
 		{
 			if( ( fromCell == toCell || moveFraction == 0 ) && fromCell == xy )
 				return new HarvestOrder( this );
-			return base.Order( xy );
+			return base.Order( game, xy );
 		}
 
 		void AcceptHarvestOrder()
diff --git a/OpenRa.Game/IOrderGenerator.cs b/OpenRa.Game/IOrderGenerator.cs
index 6dee93001b..74ec7ca9c6 100644
--- a/OpenRa.Game/IOrderGenerator.cs
+++ b/OpenRa.Game/IOrderGenerator.cs
@@ -6,7 +6,7 @@ namespace OpenRa.Game
 {
 	interface IOrderGenerator
 	{
-		//Sprite CurrentCursor( int x, int y );
-		IOrder Order( int2 xy );
+		IOrder Order( Game game, int2 xy );
+		void PrepareOverlay( Game game, int2 xy );
 	}
 }
diff --git a/OpenRa.Game/MainWindow.cs b/OpenRa.Game/MainWindow.cs
index 49c231ab60..7b1af0f8a8 100644
--- a/OpenRa.Game/MainWindow.cs
+++ b/OpenRa.Game/MainWindow.cs
@@ -89,6 +89,10 @@ namespace OpenRa.Game
 				game.viewport.Scroll(lastPos - p);
 				lastPos = p;
 			}
+
+			if (game.world.orderGenerator != null)
+				game.world.orderGenerator.PrepareOverlay(game, 
+					new int2(e.Location.X / 24, e.Location.Y / 24));
 		}
 	}
 }
diff --git a/OpenRa.Game/Mcv.cs b/OpenRa.Game/Mcv.cs
index 5e68fddb79..a5656f3dee 100644
--- a/OpenRa.Game/Mcv.cs
+++ b/OpenRa.Game/Mcv.cs
@@ -35,12 +35,12 @@ namespace OpenRa.Game
 			};
 		}
 
-		public override IOrder Order( int2 xy )
+		public override IOrder Order( Game game, int2 xy )
 		{
 			if( ( fromCell == toCell || moveFraction == 0 ) && fromCell == xy )
 				return new DeployMcvOrder( this );
 
-			return base.Order( xy );
+			return base.Order( game, xy );
 		}
 	}
 }
diff --git a/OpenRa.Game/Sidebar.cs b/OpenRa.Game/Sidebar.cs
index a3877ed5f7..2d57ce3474 100644
--- a/OpenRa.Game/Sidebar.cs
+++ b/OpenRa.Game/Sidebar.cs
@@ -48,8 +48,8 @@ namespace OpenRa.Game
 
 		public void Build(SidebarItem item)
 		{
-			if( item != null )
-				game.world.orderGenerator = new PlaceBuilding( game.players[ 1 ], item.techTreeItem.tag.ToLowerInvariant() );
+			if (item != null)
+				game.world.orderGenerator = new PlaceBuilding(game.players[1], item.techTreeItem.tag.ToLowerInvariant());
 		}
 
 		void LoadSprites(string filename)
@@ -141,12 +141,18 @@ namespace OpenRa.Game
 			this.buildingName = buildingName;
 		}
 
-		public IOrder Order( int2 xy )
+		public IOrder Order( Game game, int2 xy )
 		{
+			game.world.uiOverlay.KillOverlay();
 			// todo: check that space is free
 			return new PlaceBuildingOrder( this, xy );
 		}
 
+		public void PrepareOverlay(Game game, int2 xy)
+		{
+			game.world.uiOverlay.SetCurrentOverlay(false, xy, 2, 3);
+		}
+
 		class PlaceBuildingOrder : IOrder
 		{
 			PlaceBuilding building;
diff --git a/OpenRa.Game/UiOverlay.cs b/OpenRa.Game/UiOverlay.cs
index ebb70b987c..3b6b91cdfb 100644
--- a/OpenRa.Game/UiOverlay.cs
+++ b/OpenRa.Game/UiOverlay.cs
@@ -34,9 +34,31 @@ namespace OpenRa.Game
 
 		public void Draw()
 		{
-			spriteRenderer.DrawSprite(buildOk, new float2(48, 48), 0);
-			spriteRenderer.DrawSprite(buildBlocked, new float2(96, 48), 0);
-			spriteRenderer.Flush();
+			if (!hasOverlay)
+				return;
+
+			for (int i = 0; i < width; i++)
+				for (int j = 0; j < height; j++)
+					spriteRenderer.DrawSprite(blocked ? buildBlocked : buildOk,
+						24 * (position + new int2(i, j)), 0);
+		}
+
+		bool hasOverlay = false, blocked;
+		int2 position;
+		int width, height;
+
+		public void KillOverlay()
+		{
+			hasOverlay = false;
+		}
+
+		public void SetCurrentOverlay(bool blocked, int2 cell, int width, int height)
+		{
+			hasOverlay = true;
+			position = cell;
+			this.width = width;
+			this.height = height;
+			this.blocked = blocked;
 		}
 	}
 }
diff --git a/OpenRa.Game/Unit.cs b/OpenRa.Game/Unit.cs
index c2d87c567b..8dae1c3ff6 100644
--- a/OpenRa.Game/Unit.cs
+++ b/OpenRa.Game/Unit.cs
@@ -126,7 +126,9 @@ namespace OpenRa.Game
 		}
 
 		public int2 Location { get { return toCell; } }
-		public virtual IOrder Order(int2 xy) { return new MoveOrder(this, xy); }
+		public virtual IOrder Order(Game game, int2 xy) { return new MoveOrder(this, xy); }
 		public override Sprite[] CurrentImages { get { return animation.Images; } }
+
+		public void PrepareOverlay(Game game, int2 xy) { }
 	}
 }
diff --git a/OpenRa.Game/World.cs b/OpenRa.Game/World.cs
index a9ceb4e37a..8c0685cab3 100644
--- a/OpenRa.Game/World.cs
+++ b/OpenRa.Game/World.cs
@@ -16,7 +16,7 @@ namespace OpenRa.Game
 		Game game;
 		Region region;
 		public IOrderGenerator orderGenerator;
-		UiOverlay uiOverlay;
+		public UiOverlay uiOverlay;
 
 		public World(Renderer renderer, Game game)
 		{
@@ -40,7 +40,7 @@ namespace OpenRa.Game
 			float2 xy = (1 / 24.0f) * (new float2(e.Location) + game.viewport.Location);
 			if (orderGenerator != null)
 			{
-				IOrder order = orderGenerator.Order(new int2((int)xy.X, (int)xy.Y));
+				IOrder order = orderGenerator.Order(game, new int2((int)xy.X, (int)xy.Y));
 				game.Issue(order);
 			}
 		}
@@ -52,7 +52,7 @@ namespace OpenRa.Game
 			lastTime = t;
 
 			Range<float2> range = new Range<float2>(region.Location, region.Location + region.Size);
-
+			
 			foreach (Actor a in actors)
 			{
 				a.Tick( game, dt );