Private Declare Function GetForegroundWindow Lib "user32" () As Long
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Const GWL_EXSTYLE = (- 20 )
Private Const WS_EX_TOPMOST = &H8&

Const HWND_TOPMOST = - 1 
Const HWND_NOTOPMOST = - 2 
Const SWP_NOSIZE = &H1
Const SWP_NOMOVE = &H2
Const SWP_NOACTIVATE = &H10
Const SWP_SHOWWINDOW = &H40
Private Declare Sub SetWindowPos Lib "user32" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long)

Private Sub Form_Load()
 Call TOPMOST_Manager(Me.hwnd, HWND_TOPMOST)
 Timer1.Interval =  1000  ' 1 сек
 Timer1.Enabled = True
End Sub

Private Sub Timer1_Timer()
 Dim frmStyle As Long
 Dim activehWnd As Long
 activehWnd = GetForegroundWindow ' Получаем хэндл активной формы
 frmStyle = GetWindowLong(activehWnd, GWL_EXSTYLE) 'Получаем расширенный стиль формы
 If frmStyle And WS_EX_TOPMOST <>  0  Then 'Если бит TOPMOST установлен, тогда...
  Call TOPMOST_Manager(activehWnd, HWND_NOTOPMOST) 'Сбрасываем бит
  Call TOPMOST_Manager(Me.hwnd, HWND_TOPMOST) 'Переустанавливаем TOPMOST нашей формы
 End If
End Sub

Private Sub TOPMOST_Manager(hwnd As Long, pFlag As Integer)
 SetWindowPos hwnd, pFlag,  0 ,  0 ,  0 ,  0 , _
  SWP_NOACTIVATE Or SWP_SHOWWINDOW Or SWP_NOMOVE Or SWP_NOSIZE
End Sub

If activehWnd = Me.hwnd Then Exit Sub