You could try to use the FlashWindow api call. It toggles the titlebar from active to non-active and back.

Public Declare Function FlashWindow Lib "user32" Alias "FlashWindow" (ByVal hwnd As Long, ByVal bInvert As Long) As Long

The returnvalue is true (nonzero) if the window was active before the call.

Pass the windows hwnd, and True for bInvert to toggle the windows caption, or False to restore the original state.