VB窗体透明的问题

Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function SetLayeredWindowAttributes Lib "user32" (ByVal hwnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long

Private Const WS_EX_LAYERED = &H80000
Private Const GWL_EXSTYLE = (-20)
Private Const LWA_ALPHA = &H2
Private Const LWA_COLORKEY = &H1

Private Declare Function SetWindowPos Lib "user32" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
Private Const HWND_TOPMosT = -1
Private Const SWP_NOMOVE = &H2
Private Const SWP_NosIZE = &H1
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Private Sub Form_Load()
Me.BackColor = RGB(88, 88, 88)

SetWindowPos Me.hwnd, HWND_TOPMosT, 0, 0, 0, 0, SWP_NOMOVE Or SWP_NosIZE
Dim rtn As Long
BorderStyler = 0
rtn = GetWindowLong(hwnd, GWL_EXSTYLE)
rtn = rtn Or WS_EX_LAYERED

SetWindowLong hwnd, GWL_EXSTYLE, rtn

SetLayeredWindowAttributes hwnd, RGB(88, 88, 88), 0, LWA_COLORKEY
End Sub