Hi All

I've got a rather frustrating problem. I've got a project
with a MDI Form and a Child Form. On the child form is a timer that starts a rather resource intensive task, I want to switch off the timer when the application becomes inactive.

I can trap this event if the form is minimized but what do I trap if the app is deactivated when someone alt-tabs to a different program.

Cheers

Ray


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I'd rather be fishing

You need to subclass MDI form for WM_ACTIVATE message

' MDI form code

Option Explicit Const GWL_WNDPROC = (-4) Private Sub MDIForm_Load()     hWndProc = SetWindowLong(Me.hwnd, GWL_WNDPROC, AddressOf WindowProc) End Sub Private Sub MDIForm_Unload(Cancel As Integer)     SetWindowLong Me.hwnd, GWL_WNDPROC, hWndProc End Sub

'module code

Option Explicit Const WM_ACTIVATE = &H6 Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long Declare Function SetClipboardViewer Lib "user32" (ByVal hwnd As Long) As Long Public hWndProc As Long Public Function WindowProc(ByVal hwnd As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long     WindowProc = CallWindowProc(hWndProc, hwnd, uMsg, wParam, lParam)          If uMsg = WM_ACTIVATE Then         Select Case wParam             Case 0                 Debug.Print "Deactivated"             Case 1                 Debug.Print "Activated"             Case 2                 Debug.Print "Activated with mouse"         End Select     End If End Function

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If you find the answer helpful, please mark this topic as solved.

Thanks Goran.

I'll try your method. Hopefully without the headaches I've had subclassing forms in the past.



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I'd rather be fishing