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 Sub Form_Load()
Dim rtn As Long

Me.BackColor = RGB(255, 255, 255)
BorderStyler = 0
rtn = GetWindowLong(hWnd, GWL_EXSTYLE)
rtn = rtn Or WS_EX_LAYERED
SetWindowLong hWnd, GWL_EXSTYLE, rtn
SetLayeredWindowAttributes hWnd, RGB(255, 255, 255), 100, LWA_COLORKEY

End Sub
这里用到的是VB API函数!