diff --git a/OpenRa.Game/MainWindow.cs b/OpenRa.Game/MainWindow.cs
index ca823ea92f..c8eeabfa6b 100644
--- a/OpenRa.Game/MainWindow.cs
+++ b/OpenRa.Game/MainWindow.cs
@@ -22,6 +22,7 @@ namespace OpenRa.Game
 		TreeCache treeCache;
 		TerrainRenderer terrain;
 		Sidebar sidebar;
+		Viewport viewport;
 
 		static Size GetResolution(Settings settings)
 		{
@@ -36,6 +37,7 @@ namespace OpenRa.Game
 			FormBorderStyle = FormBorderStyle.None;
 			BackColor = Color.Black;
 			renderer = new Renderer(this, GetResolution(settings), false);
+			viewport = new Viewport(ClientSize);
 			Visible = true;
 
 			SheetBuilder.Initialize(renderer.Device);
@@ -71,7 +73,7 @@ namespace OpenRa.Game
 			}
 		}
 
-		PointF scrollPos;
+		
 		int x1,y1;
 
 		protected override void OnMouseDown(MouseEventArgs e)
@@ -88,6 +90,7 @@ namespace OpenRa.Game
 
 			if (e.Button != 0)
 			{
+				PointF scrollPos = viewport.ScrollPosition;
 				scrollPos.X += x1 - e.X;
 				scrollPos.Y += y1 - e.Y;
 
@@ -96,25 +99,24 @@ namespace OpenRa.Game
 
 				scrollPos.X = Util.Constrain(scrollPos.X, new Range<float>(0, map.Width * 24 - ClientSize.Width + 128));
 				scrollPos.Y = Util.Constrain(scrollPos.Y, new Range<float>(0, map.Height * 24 - ClientSize.Height));
+				viewport.ScrollPosition = scrollPos;
 			}
 		}
 
 		void Frame()
 		{
-			PointF r1 = new PointF(2.0f / ClientSize.Width, -2.0f / ClientSize.Height);
+			PointF r1 = new PointF(2.0f / viewport.ClientSize.Width, -2.0f / viewport.ClientSize.Height);
 			PointF r2 = new PointF(-1, 1);
 
-			renderer.BeginFrame(r1, r2, scrollPos);
+			renderer.BeginFrame(r1, r2, viewport.ScrollPosition);
 
-			renderer.Device.EnableScissor(0, 0, ClientSize.Width - 128, ClientSize.Height);
-			terrain.Draw( ClientSize, scrollPos );
+			renderer.Device.EnableScissor(0, 0, viewport.ClientSize.Width - 128, viewport.ClientSize.Height);
+			terrain.Draw(viewport);
 
-			world.Draw(renderer,
-				new Range<float>(scrollPos.X, scrollPos.X + ClientSize.Width),
-				new Range<float>(scrollPos.Y, scrollPos.Y + ClientSize.Height));
+			world.Draw(renderer, viewport);
 
 			renderer.Device.DisableScissor();
-			sidebar.Paint(ClientSize, scrollPos);
+			sidebar.Paint(viewport);
 
 			renderer.EndFrame();
 		}
diff --git a/OpenRa.Game/OpenRa.Game.csproj b/OpenRa.Game/OpenRa.Game.csproj
index a699d11977..de5121cc69 100644
--- a/OpenRa.Game/OpenRa.Game.csproj
+++ b/OpenRa.Game/OpenRa.Game.csproj
@@ -64,6 +64,7 @@
     <Compile Include="UnitSheetBuilder.cs" />
     <Compile Include="Util.cs" />
     <Compile Include="Vertex.cs" />
+    <Compile Include="Viewport.cs" />
     <Compile Include="World.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/OpenRa.Game/Sidebar.cs b/OpenRa.Game/Sidebar.cs
index 029354cb47..48cec2ff38 100644
--- a/OpenRa.Game/Sidebar.cs
+++ b/OpenRa.Game/Sidebar.cs
@@ -54,10 +54,10 @@ namespace OpenRa.Game
 				DrawSprite(blank, ref p);
 		}
 
-		public void Paint(Size clientSize, PointF scrollOffset)
+		public void Paint(Viewport viewport)
 		{
-			PointF buildPos = new PointF(clientSize.Width - 128 + scrollOffset.X, scrollOffset.Y);
-			PointF unitPos = new PointF(clientSize.Width - 64 + scrollOffset.X, scrollOffset.Y);
+			PointF buildPos = new PointF(viewport.ClientSize.Width - 128 + viewport.ScrollPosition.X, viewport.ScrollPosition.Y);
+			PointF unitPos = new PointF(viewport.ClientSize.Width - 64 + viewport.ScrollPosition.X, viewport.ScrollPosition.Y);
 			
 			foreach (Item i in techTree.BuildableItems)
 			{
@@ -70,8 +70,8 @@ namespace OpenRa.Game
 					DrawSprite( sprite, ref unitPos );
 			}
 
-			Fill(clientSize, buildPos);
-			Fill(clientSize, unitPos);
+			Fill(viewport.ClientSize, buildPos);
+			Fill(viewport.ClientSize, unitPos);
 
 			spriteRenderer.Flush();
 		}
diff --git a/OpenRa.Game/TerrainRenderer.cs b/OpenRa.Game/TerrainRenderer.cs
index 202fc25e34..6448c900f2 100644
--- a/OpenRa.Game/TerrainRenderer.cs
+++ b/OpenRa.Game/TerrainRenderer.cs
@@ -54,14 +54,14 @@ namespace OpenRa.Game
 			indexBuffer.SetData(indices.ToArray());
 		}
 
-		public void Draw( Size screenSize, PointF scrollPos )
+		public void Draw( Viewport viewport )
 		{
 			int indicesPerRow = map.Width * 6;
 			int verticesPerRow = map.Width * 4;
 
-			int visibleRows = (int)(screenSize.Height / 24.0f + 2);
+			int visibleRows = (int)(viewport.ClientSize.Height / 24.0f + 2);
 
-			int firstRow = (int)(scrollPos.Y / 24.0f);
+			int firstRow = (int)(viewport.ScrollPosition.Y / 24.0f);
 			int lastRow = firstRow + visibleRows;
 
 			if (lastRow < 0 || firstRow > map.Height)
diff --git a/OpenRa.Game/Viewport.cs b/OpenRa.Game/Viewport.cs
new file mode 100644
index 0000000000..380062a777
--- /dev/null
+++ b/OpenRa.Game/Viewport.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Drawing;
+
+namespace OpenRa.Game
+{
+	class Viewport
+	{
+		readonly Size clientSize;
+		PointF scrollPosition;
+
+		public PointF ScrollPosition
+		{
+			get { return scrollPosition; }
+			set { scrollPosition = value; }
+		}
+
+		public Size ClientSize
+		{
+			get { return clientSize; }
+		} 
+
+
+		public Viewport(Size clientSize)
+		{
+			this.clientSize = clientSize;
+		}
+	}
+}
diff --git a/OpenRa.Game/World.cs b/OpenRa.Game/World.cs
index c879d6b1cf..d8d9f627e4 100644
--- a/OpenRa.Game/World.cs
+++ b/OpenRa.Game/World.cs
@@ -19,8 +19,10 @@ namespace OpenRa.Game
 
 		public void Add(Actor a) { actors.Add(a); }
 
-		public void Draw(Renderer renderer, Range<float> xr, Range<float> yr)
+		public void Draw(Renderer renderer, Viewport viewport)
 		{
+			Range<float> xr = new Range<float>(viewport.ScrollPosition.X, viewport.ScrollPosition.X + viewport.ClientSize.Width);
+			Range<float> yr = new Range<float>(viewport.ScrollPosition.Y, viewport.ScrollPosition.Y + viewport.ClientSize.Height);
 			foreach (Actor a in actors)
 			{
 				Sprite[] images = a.CurrentImages;