DisableXCommand

Declare Function GetSystemMenu Lib "User32" (ByVal hWnd As Integer, ByVal bRevert As Integer) As Integer
Declare Function RemoveMenu Lib "User32" (ByVal hMenu As Integer, ByVal nPosition As Integer, ByVal wFlags As Integer) As Integer
Global Const MF_BYPOSITION = &H400

'Nell'evento Load del form1 mettete:


Private Sub Form_Load()
SystemMenu% = GetSystemMenu(hWnd, 0)
Res% = RemoveMenu(SystemMenu%, 6, MF_BYPOSITION)
End Sub

'Eseguite l'applicazione (F5) e vedrete che il pulsante

'("chiudi")e' disabilitato.