Option Explicit

Const LWA_COLORKEY = &H1
'Const LWA_ALPHA = &H2
Const LWA_ALPHA = &H3
Const GWL_EXSTYLE = (- 20 )
Const WS_EX_LAYERED = &H80000

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 Sub Form_Load()
    Dim Ret As Long
    'добавляем окну возможность прозрачности
    Ret = GetWindowLong(Me.hWnd, GWL_EXSTYLE)
    Ret = Ret Or WS_EX_LAYERED
    SetWindowLong Me.hWnd, GWL_EXSTYLE, Ret
    'делаем белый цвет прозрачным
    SetLayeredWindowAttributes Me.hWnd, vbWhite,  255 , LWA_ALPHA
    'делаем форму белой, чтобы она стала прозрачной
    Me.BackColor = vbWhite
End Sub