When the user will try to end this program by clicking the X button, by pressing Alt + F4, or by any other way, a message box will pop up and will ask him for confirmation.
Private Sub Form_QueryUnload(Cancel As Integer,
UnloadMode As Integer)
Dim Answer As Integer
Answer = MsgBox("Are you sure you want to exit this program?", _
vbQuestion + vbYesNo, "Confirmation")
If Answer = vbNo Then Cancel = -1