about Opacity

[WolfWorld]

I am going on a project name OpenIndex but the Opacity of the png back ground become grey

_GDIPlus_Startup ()

FileInstall('Image\Background.png', @TempDir & '\openimage1', 1);-

Local $hImage = _GDIPlus_ImageLoadFromFile (@TempDir & '\openimage1');-

FileDelete(@TempDir & '\openimage1')

Local $width = _GDIPlus_ImageGetWidth ($hImage)

Local $height = _GDIPlus_ImageGetHeight ($hImage)

$Main_Gui = GUICreate('OpenIndex V.' & $Version, $width, $height, -1, -1,$WS_POPUP)

GUISetState();-

Local $hGraphic = _GDIPlus_GraphicsCreateFromHWND ($Main_Gui)

Local $hBitmap = _GDIPlus_BitmapCreateFromGraphics($Width, $Height, $hGraphic)

_GDIPlus_GraphicsDrawImage ($hGraphic, $hImage, 0, 0)

GUIRegisterMsg($WM_NCHITTEST, 'WM_NCHITTEST');-

_GDIPlus_GraphicsDispose ($hGraphic)

_GDIPlus_ImageDispose ($hImage)

_GDIPlus_ShutDown ()