diff --git a/Source/OpenTK/Platform/Factory.cs b/Source/OpenTK/Platform/Factory.cs
index c7dbaed7..f4fcfb22 100644
--- a/Source/OpenTK/Platform/Factory.cs
+++ b/Source/OpenTK/Platform/Factory.cs
@@ -33,7 +33,7 @@ namespace OpenTK.Platform
 {
     using Graphics;
 
-    class Factory : IPlatformFactory
+    sealed class Factory : IPlatformFactory
     {
         #region Fields
 
@@ -125,7 +125,12 @@ namespace OpenTK.Platform
                 throw new PlatformNotSupportedException(error_string);
             }
 
-            public IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool DirectRendering, int major, int minor, GraphicsContextFlags flags)
+            public IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags)
+            {
+                throw new PlatformNotSupportedException(error_string);
+            }
+
+            public IGraphicsContext CreateESContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, int major, int minor, GraphicsContextFlags flags)
             {
                 throw new PlatformNotSupportedException(error_string);
             }
diff --git a/Source/OpenTK/Platform/IPlatformFactory.cs b/Source/OpenTK/Platform/IPlatformFactory.cs
index 65209e34..0240aebf 100644
--- a/Source/OpenTK/Platform/IPlatformFactory.cs
+++ b/Source/OpenTK/Platform/IPlatformFactory.cs
@@ -41,7 +41,7 @@ namespace OpenTK.Platform
 
         IDisplayDeviceDriver CreateDisplayDeviceDriver();
 
-        IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool DirectRendering, int major, int minor, GraphicsContextFlags flags);
+        IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags);
 
         OpenTK.Graphics.GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext();
         
diff --git a/Source/OpenTK/Platform/MacOS/MacOSFactory.cs b/Source/OpenTK/Platform/MacOS/MacOSFactory.cs
index a3789a83..756a03aa 100644
--- a/Source/OpenTK/Platform/MacOS/MacOSFactory.cs
+++ b/Source/OpenTK/Platform/MacOS/MacOSFactory.cs
@@ -37,27 +37,27 @@ namespace OpenTK.Platform.MacOS
     {
         #region IPlatformFactory Members
 
-        public INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
+        public virtual INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
         {
             return new CarbonGLNative(x, y, width, height, title, mode, options, device);
         }
 
-        public IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
+        public virtual IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
         {
             return new CarbonGLControl(mode, owner);
         }
 
-        public IDisplayDeviceDriver CreateDisplayDeviceDriver()
+        public virtual IDisplayDeviceDriver CreateDisplayDeviceDriver()
         {
             return new QuartzDisplayDeviceDriver();
         }
 
-        public IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool DirectRendering, int major, int minor, GraphicsContextFlags flags)
+        public virtual IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags)
         {
             return new AglContext(mode, window, shareContext);
         }
 
-        public GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
+        public virtual GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
         {
             return (GraphicsContext.GetCurrentContextDelegate)delegate
             {
@@ -65,12 +65,12 @@ namespace OpenTK.Platform.MacOS
             };
         }
 
-        public IGraphicsMode CreateGraphicsMode()
+        public virtual IGraphicsMode CreateGraphicsMode()
         {
             return new MacOSGraphicsMode();
         }
 
-        public OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
+        public virtual OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
         {
             throw new NotImplementedException();
         }
diff --git a/Source/OpenTK/Platform/Windows/WinFactory.cs b/Source/OpenTK/Platform/Windows/WinFactory.cs
index 12c4a4d9..8aaf9353 100644
--- a/Source/OpenTK/Platform/Windows/WinFactory.cs
+++ b/Source/OpenTK/Platform/Windows/WinFactory.cs
@@ -32,33 +32,33 @@ using System.Text;
 namespace OpenTK.Platform.Windows
 {
     using Graphics;
-using OpenTK.Input;
+    using OpenTK.Input;
 
     class WinFactory : IPlatformFactory 
     {
         #region IPlatformFactory Members
 
-        public INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
+        public virtual INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
         {
             return new WinGLNative(x, y, width, height, title, options, device);
         }
 
-        public IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
+        public virtual IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
         {
             return new WinGLControl(mode, owner);
         }
 
-        public IDisplayDeviceDriver CreateDisplayDeviceDriver()
+        public virtual IDisplayDeviceDriver CreateDisplayDeviceDriver()
         {
             return new WinDisplayDeviceDriver();
         }
 
-        public IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags)
+        public virtual IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags)
         {
             return new WinGLContext(mode, (WinWindowInfo)window, shareContext, major, minor, flags);
         }
 
-        public GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
+        public virtual GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
         {
             return (GraphicsContext.GetCurrentContextDelegate)delegate
             {
@@ -66,12 +66,12 @@ using OpenTK.Input;
             };
         }
 
-        public IGraphicsMode CreateGraphicsMode()
+        public virtual IGraphicsMode CreateGraphicsMode()
         {
             return new WinGraphicsMode();
         }
 
-        public OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
+        public virtual OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
         {
             throw new NotImplementedException();
         }
diff --git a/Source/OpenTK/Platform/X11/X11Factory.cs b/Source/OpenTK/Platform/X11/X11Factory.cs
index 63f55fba..6b1c43f0 100644
--- a/Source/OpenTK/Platform/X11/X11Factory.cs
+++ b/Source/OpenTK/Platform/X11/X11Factory.cs
@@ -10,27 +10,27 @@ namespace OpenTK.Platform.X11
     {
         #region IPlatformFactory Members
 
-        public INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
+        public virtual INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
         {
             return new X11GLNative(x, y, width, height, title, mode, options, device);
         }
 
-        public IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
+        public virtual IGLControl CreateGLControl(GraphicsMode mode, GLControl owner)
         {
             return new X11GLControl(mode, owner);
         }
 
-        public IDisplayDeviceDriver CreateDisplayDeviceDriver()
+        public virtual IDisplayDeviceDriver CreateDisplayDeviceDriver()
         {
             return new X11XrandrDisplayDevice();
         }
 
-        public IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool DirectRendering, int major, int minor, GraphicsContextFlags flags)
+        public virtual IGraphicsContext CreateGLContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, bool directRendering, int major, int minor, GraphicsContextFlags flags)
         {
-            return new X11GLContext(mode, window, shareContext, DirectRendering, major, minor, flags);
+            return new X11GLContext(mode, window, shareContext, directRendering, major, minor, flags);
         }
 
-        public OpenTK.Graphics.GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
+        public virtual OpenTK.Graphics.GraphicsContext.GetCurrentContextDelegate CreateGetCurrentGraphicsContext()
         {
             return (GraphicsContext.GetCurrentContextDelegate)delegate
             {
@@ -38,12 +38,12 @@ namespace OpenTK.Platform.X11
             };
         }
 
-        public IGraphicsMode CreateGraphicsMode()
+        public virtual IGraphicsMode CreateGraphicsMode()
         {
             return new X11GraphicsMode();
         }
-        
-        public OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
+
+        public virtual OpenTK.Input.IKeyboardDriver CreateKeyboardDriver()
         {
             throw new NotImplementedException();
         }