VB编程的菜鸟问题

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 GetWindowLong Lib "user32" _
Alias "GetWindowLongA" _
(ByVal hwnd As Long, _
ByVal nIndex As Long) _
As Long

Private Const GWL_EXSTYLE = (-20)
Private Const LWA_ALPHA As Long = &H2
Private Const WS_EX_LAYERED As Long = &H80000

Private Declare Function SetLayeredWindowAttributes Lib "user32" _
(ByVal hwnd As Long, _
ByVal crKey As Long, _
ByVal bAlpha As Long, _
ByVal dwFlags As Long) _
As Long

Private Sub Command1_Click()
Dim p As Long
p = GetWindowLong(Me.hwnd, GWL_EXSTYLE) '取得当前窗口属性
Call SetWindowLong(Me.hwnd, GWL_EXSTYLE, p Or WS_EX_LAYERED)
'加上一个透明属性
Call SetLayeredWindowAttributes(Me.hwnd, 0, 0, LWA_ALPHA)
End Sub