CODE

Option Compare Database
Option Explicit

Private Type LASTINPUTINFO
        cbSize As Long
        dwTime As Long
End Type

Private Declare Function GetLastInputInfo Lib "user32" (li As LASTINPUTINFO) As Long
Private Declare Function GetTickCount Lib "kernel32" () As Long

Private mvarIdleTime As Long

Private Sub Command0_Click()
        DetectIdle 5000, 500
End Sub

Private Sub Form_Timer()
    If GetTickCount - GetInputTick > mvarIdleTime Then
        MsgBox "IDLE for " & CStr(GetTickCount - GetInputTick) & "ms"
    End If
End Sub

Private Sub DetectIdle(ByVal lIdleTime As Long, ByVal lTimerInterval As Long)    
    TimerInterval = lTimerInterval 'also activates the Timer if interval<>0
    mvarIdleTime = lIdleTime
End Sub

' Returns system tick count when last input occurred
Private Function GetInputTick() As Long
    Static LastInputTick As Long
    
    Dim myLI As LASTINPUTINFO
    myLI.cbSize = Len(myLI)
    GetLastInputInfo myLI
    GetInputTick = myLI.dwTime
End Function