c#window mobile 半透明效果

E:\vsproject\WifiMe\WifiMe\bin\Debug\img\battery.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\camera.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\camera_p.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\icegirl.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\map.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\map_p.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\signal.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\topbar.BMP E:\vsproject\WifiMe\WifiMe\bin\Debug\img\toplock.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\img\wallpaper.bmp E:\vsproject\WifiMe\WifiMe\bin\Debug\WifiMe.exe E:\vsproject\WifiMe\WifiMe\bin\Debug\WifiMe.pdb E:\vsproject\WifiMe\WifiMe\obj\Debug\ResolveAssemblyReference.cache E:\vsproject\WifiMe\WifiMe\obj\Debug\AlphaBlendTest.main.resources E:\vsproject\WifiMe\WifiMe\obj\Debug\WifiMe.Properties.Resources.resources E:\vsproject\WifiMe\WifiMe\obj\Debug\AlphaBlendTest.csproj.GenerateResource.Cache E:\vsproject\WifiMe\WifiMe\obj\Debug\WifiMe.exe E:\vsproject\WifiMe\WifiMe\obj\Debug\WifiMe.pdb