Allez va,
Regarde ce que ferait ceci :
Private Declare Function FindWindow Lib "User32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) 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 GetWindowLong Lib "User32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
Private Sub UserForm_Initialize()
Dim S As Long, H As Long
H = FindWindow(vbNullString, Me.Caption)
S = GetWindowLong(H, -16) Or &H70000
SetWindowLong H, -16, S
End Sub