Create a new .exe project, add a module to it with the following code: Public Declare Function FlashWindow _ Lib "user32" (ByVal hwnd As Long, _ ByVal bInvert As Long) As Long Put a timer and 2 commandbuttons on form1 with these properties: command1.caption="Start" command2.caption="Stop" timer1.interval=500 'flashes every 1/2 second timer1.enabled=false Code Private Sub Timer1_Timer() a& = FlashWindow(Me.hwnd, 1) End Sub Private Sub Command1_Click() Timer1.Enabled = True End Sub Private Sub Command2_Click() Timer1.Enabled = False End Sub Execute the app. (F5) and click the buttons.