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_Activate()
'con estos parametros el form permanece siempre visible y no se modifica el tamaño, o la posicion
SetWindowPos Me.hWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE Or SWP_SHOWWINDOW Or SWP_NOMOVE Or SWP_NOSIZE
End Sub
'Si el formulario se sigue ocultando detras de alguna ventana, simplemente copia este codiga dentro del evento Paint() del form.