Prevent Windows Shutdown

[gigemboy]

Here is a little code snippet that prevents the windows from shutting down if your app is running, it intercepts the WM_QUERYENDSESSION message that is sent to the open windows on a system shutdown, and cancels the message.

'constants needed, form level
    Private Const WM_QUERYENDSESSION As System.Int32 = &H11
    Private Const WM_CANCELMODE As System.Int32 = &H1F
 
    'the sub to intercept the windows messages
    Protected Overrides Sub WndProc(ByRef ex As Message)
        If ex.Msg = WM_QUERYENDSESSION Then
            'cancel the message
            Dim MyMsg As New Message
            MyMsg.Msg = WM_CANCELMODE
            MyBase.WndProc(MyMsg)
        Else
            'send the message as normal
            MyBase.WndProc(ex)
        End If
    End Sub