Attribute VB_Name = "ModTransparent"
Option Explicit
Private Const WS_EX_LAYERED = &H80000
Private Const LWA_ALPHA = &H2
Private Const GWL_EXSTYLE = (-20)

Declare Function SetLayeredWindowAttributes Lib "user32" (ByVal hWnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Boolean
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long


Public Sub RendreTransparent(etat As Boolean, Fenetre As Form, Optional ByVal Alpha As Byte = 255)
If etat Then
    SetWindowLong Fenetre.hWnd, GWL_EXSTYLE, GetWindowLong(Fenetre.hWnd, GWL_EXSTYLE) Or WS_EX_LAYERED
    SetLayeredWindowAttributes Fenêtre.hWnd, 0, Alpha, LWA_ALPHA
Else
    SetWindowLong Fenetre.hWnd, GWL_EXSTYLE, GetWindowLong(Fenetre.hWnd, GWL_EXSTYLE) - WS_EX_LAYERED
End If
End Sub