ACC2: How to Detect When MS Access Is Activated or Deactivated

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The following steps demonstrate how to create a form called Access_Activation that will detect when Microsoft Access is activated or deactivated. The form contains two empty procedures called Access_Activate and Access_Deactivate into which you can insert the code you want to run when Microsoft Access is activated or deactivated. When the Access_Activation form is open in Form view, switching to Microsoft Access from another application will cause the Access_Activate procedure to run. Switching from Microsoft Access to another application will cause the Access_Deactivate procedure to run.

The Access_Activation form must be open in order to detect when Microsoft Access is activated and deactivated. To make sure the form is always open, you could open the form in a hidden state in your database's Autoexec macro. To open the form in a hidden state, set the Window Mode argument of the OpenForm macro action to Hidden.

1. Open any database and create a blank new form. Set the following properties for the form:
   

         OnTimer: [Event Procedure]
         TimerInterval: 500
   						

2. From the View menu, choose Code. Type the following lines in the form module's Declarations section.
   
   NOTE: In the following sample code, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this code in Access Basic.
   

         Option Explicit
   						

         Declare Function GetActiveWindow Lib "User" () As Integer
         Declare Function GetParent Lib "User" (ByVal hWnd As Integer) _
         As Integer
         Declare Function GetFocus Lib "User" () As Integer
   						

3. Enter the following code for the OnTimer property event procedure:
   

         Sub Form_Timer ()
            Dim RetVal As Integer
            Dim CurrhWnd As Integer
            Dim AccesshWnd As Integer
            Static ActiveApphWnd As Integer
   
            ' Get the Microsoft Access window handle (hWnd).
            AccesshWnd = GetAccesshWnd()
   
            ' Get the active application window handle (hWnd).
            CurrhWnd = GetActiveApphWnd()
   
            ' The first time through, just record the current
            ' window handle.
            If ActiveApphWnd = 0 Then
               ActiveApphWnd = CurrhWnd
               Exit Sub
            End If
   
            ' Determine if the current window handle differs from the
            ' previous window handle (focus change).
            If CurrhWnd <> ActiveApphWnd Then
               ' Record the current window handle.
               ActiveApphWnd = CurrhWnd
   
               ' Determine if the current handle is the Microsoft Access
               ' handle (activate Microsoft Access?).
               If ActiveApphWnd = AccesshWnd Then
                  Access_Activate
               Else
                  Access_Deactivate
               End If
            End If
         End Sub
   						

4. Enter the following procedures in the form module:
   

         Sub Access_Activate ()
            ' Insert the code that you want to run when Microsoft Access
            ' is activated here.
         End Sub
   
         Sub Access_Deactivate ()
            ' Insert the code that you want to run when Microsoft Access
            ' is deactivated here.
         End Sub
   
         Function GetAccesshWnd ()
            GetAccesshWnd = GetTopMosthWnd(Me.hWnd)
         End Function
   
         Function GetActiveApphWnd ()
            GetActiveApphWnd = GetTopMosthWnd(GetActiveWindow())
         End Function
   
         Function GetTopMosthWnd (ByVal hWnd)
            Dim hWndTopMost As Integer
            hWndTopMost = hWnd
   
            ' Find the top window without a parent window.
            While hWnd <> 0
               hWndTopMost = hWnd
               hWnd = GetParent(hWnd)
            Wend
   
            GetTopMosthWnd = hWndTopMost
         End Function
   						

5. Close the module and save the form as Access_Activation.

How to Use the Access_Activation Form

The following steps demonstrate how to use the Access_Activation form:

1. Open any database and create the Access_Activation form as described above.
2. Substitute the following Access_Activate procedure for the Access_Activate procedure you created in step 4 above:
   

         Sub Access_Activate ()
            MsgBox "Microsoft Access was activated"
         End Sub
   						

3. View the Access_Activation form in Form view.
4. Press ALT+TAB to switch from Microsoft Access to another application.
5. Press ALT+TAB to switch back to Microsoft Access. A message box with the text "Microsoft Access was activated" is displayed.