diff -r 3145aadca3d2 -r 0c551e8818e0 External/Aga.Controls/BitmapHelper.cs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/External/Aga.Controls/BitmapHelper.cs	Sun May 27 15:16:19 2012 +0000
@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Drawing;
+using System.Runtime.InteropServices;
+using System.Drawing.Imaging;
+
+namespace Aga.Controls
+{
+	public static class BitmapHelper
+	{
+		[StructLayout(LayoutKind.Sequential)]
+		private struct PixelData
+		{
+			public byte B;
+			public byte G;
+			public byte R;
+			public byte A;
+		}
+
+		public static void SetAlphaChanelValue(Bitmap image, byte value)
+		{
+			if (image == null)
+				throw new ArgumentNullException("image");
+			if (image.PixelFormat != PixelFormat.Format32bppArgb)
+				throw new ArgumentException("Wrong PixelFormat");
+
+			BitmapData bitmapData = image.LockBits(new Rectangle(0, 0, image.Width, image.Height),
+									 ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
+			unsafe
+			{
+				PixelData* pPixel = (PixelData*)bitmapData.Scan0;
+				for (int i = 0; i < bitmapData.Height; i++)
+				{
+					for (int j = 0; j < bitmapData.Width; j++)
+					{
+						pPixel->A = value;
+						pPixel++;
+					}
+					pPixel += bitmapData.Stride - (bitmapData.Width * 4);
+				}
+			}
+			image.UnlockBits(bitmapData);
+		}
+	}
+}