ACC2000: Screen.ActiveForm Returns the Main Form, Not the Subform (210210)

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How To Create the Set_Screen_ActiveSubformControl() Function

To create the Set_Screen_ActiveSubformControl() function, follow these steps:

1. Create a module and type the following lines in the Declarations section if they are not already there:

   Option Explicit
   Dim Screen_ActiveSubformControl As Control
   					

2. Type the following two procedures:

   Function Set_Screen_ActiveSubformControl()
     Dim frmActive As Form, ctlActive As Control
     Dim hWndParent As Long
   
     ' Clear the control variable.
     Set Screen_ActiveSubformControl = Nothing
   
     ' Assume a subform is not active.
     Set_Screen_ActiveSubformControl = False
   
     ' Get the active form and control.
     On Error Resume Next
     Set frmActive = Screen.ActiveForm
     Set ctlActive = Screen.ActiveControl
     If Err <> 0 Then Exit Function
   
     ' Get the unique window handle identifying the form
     ' .. the active control is on.
     hWndParent = ctlActive.Parent.Properties("hWnd")
   
     ' If the active form window handle is the same as the window
     ' handle of the form the active control is on, then we are on the
     ' mainform, so exit.
     If hWndParent = frmActive.hWnd Then Exit Function
   
     ' Find a subform control that has a window handle matching the
     ' .. window handle of the form the active control is on.
     Set_Screen_ActiveSubformControl = FindSubform(frmActive, _
         hWndParent)
   
   End Function
   
   Function FindSubform(frmSearch As Form, hWndFind As Long)
     Dim i As Integer
     On Error GoTo Err_FindSubForm
   
     ' Assume we will find a subform control with a window
     ' .. handle matching hWndFind.
     FindSubform = True
   
     ' Visit each control on the form frmSearch.
     For i = 0 To frmSearch.Count - 1
        ' If the control is a subform control...
        If TypeOf frmSearch(i) Is SubForm Then
           ' .. does the window handle match the one we are looking
           ' for?
        If frmSearch(i).Form.hWnd = hWndFind Then
           ' We found it! Set the global control variable and exit.
           Set Screen_ActiveSubformControl = frmSearch(i)
           Exit Function
        Else
           ' Otherwise, search this subform control (recursively)
           ' .. to see if it contains a sub-subform control
           ' .. with a window handle matching the one we are
           ' .. interested in.
   
           ' If we found a subform control, then exit.
           If FindSubform(frmSearch(i).Form, hWndFind) Then
              Exit Function
           End If
        End If
     End If
   Next i
   
   Bye_FindSubform:
   ' If we didn't exit the function earlier, then there is no
   ' .. subform or sub-subform control on this form that has a window
   ' .. handle matching the one we are interested in, so return false.
   FindSubform = False
   Exit Function
   
   Err_FindSubForm:
     MsgBox Error$, 16, "FindSubform"
     Resume Bye_FindSubform
   End Function
   					

How to Use the Set_Screen_ActiveSubformControl() Function

To use the Set_Screen_ActiveSubformControl() function to determine what subform control contains the Screen.ActiveControl, follow these steps:

CAUTION: If you follow the steps in this example, you modify the sample database Northwind.mdb. You may want to back up the Northwind.mdb file and follow these steps on a copy of the database.

1. Start Microsoft Access and open the sample database Northwind.mdb or the sample project NorthwindCS.adp.
2. Create the functions described in the previous section "How To Create the Set_Screen_ActiveSubformControl() Function."
3. Create a new macro called AutoKeys as follows:

      Macro Name   Action      Action Arguments
      -------------------------------------------------------------------
      {F2}         RunCode     Function Name: =DisplayActiveSubformName()
   					

4. Add the following function to the module that you created in step 1:

   Function DisplayActiveSubformName()
      Dim Msg As String
      Dim CR As String
      CR = Chr$(13)  ' Carriage Return.
   
      If Set_Screen_ActiveSubformControl() = False Then
         Msg = "There is no active subform!"
      Else
         Msg = "Active Form Name = " & Screen.ActiveForm.Name
         Msg = Msg & CR
         Msg = Msg & "Active ControlName = " & Screen.ActiveControl.Name
         Msg = Msg & CR
         Msg = Msg & "Active Subform ControlName = "
         Msg = Msg & Screen_ActiveSubformControl.Name
         Msg = Msg & CR
         Msg = Msg & "Active Subform Form Name = "
         Msg = Msg & Screen_ActiveSubformControl.Form.Name
      End If
   
      MsgBox Msg
   
   End Function
   					

5. Open the Customers form in Design view, and then press F11 to switch to the Database window.
6. Drag the Orders form from the Database window to the bottom of the Customers form to create a subform control. This action enables you to test the function on a subform and a sub-subform.
7. Select the new subform control and set the following properties:

   Name: Testing 123
   SourceObject: Orders

8. View the Customers form in Form view. Note that the Orders subform contains only orders for the current customer.
9. Set the focus to a control in the Customers form, the Orders form (subform), or the Orders Subform (sub-subform), and then press the F2 key to run the macro.