Added ResetTransform method to Context

Xwt.Gtk/Xwt.GtkBackend/ContextBackendHandler.cs

@@ -254,7 +254,13 @@ namespace Xwt.GtkBackend
 			ctx.Context.Fill ();*/
 		}
 		
-		public void Rotate (object backend, double angle)
+		public void ResetTransform (object backend)
+		{
+			GtkContext gc = (GtkContext)backend;
+			gc.Context.IdentityMatrix();
+		}
+
+        public void Rotate (object backend, double angle)
 		{
 			GtkContext gc = (GtkContext)backend;
 			gc.Context.Rotate ((angle * System.Math.PI) / 180);

Xwt/Xwt.Backends/IContextBackendHandler.cs

@@ -87,6 +87,8 @@ namespace Xwt.Backends
 		
 		void DrawImage (object backend, object img, double x, double y, double width, double height, double alpha);
 
+		void ResetTransform (object backend);
+
 		void Rotate (object backend, double angle);
 		
 		void Translate (object backend, double tx, double ty);

Xwt/Xwt.Drawing/Context.cs

@@ -246,6 +246,15 @@ namespace Xwt.Drawing
 			handler.DrawImage (Backend, GetBackend (img), rect.X, rect.Y, rect.Width, rect.Height, alpha);
 		}
 
+        /// <summary>
+        /// Resets the Current Trasnformation Matrix (CTM) to the Identity Matrix
+        /// </summary>
+		public void ResetTransform ()
+		{
+			handler.ResetTransform (Backend);
+		}
+		
+		
 		/// <summary>
 		/// Applies a rotation transformation
 		/// </summary>