🚀 go-pugleaf

I have defined a RegisteredWindowsMessage like this:

static const UINT UWM_U_R_ME = 
::RegisterWindowMessage("UWM_U_R_ME-5B76225D-E886-4ce1-BE1F-A983F759EC8A");

Now I need to map the message in the application that is to receive it.

The Help File example looks like this:

#define CM_CHANGECOLOR (WM_APP + 400)
...
BEGIN_MESSAGE_MAP
   MESSAGE_HANDLER(CM_CHANGECOLOR, TMessage, CMChangeColor)
END_MESSAGE_MAP(TControl)

but that is for a constant message not a Registered Windows Message.

The mapping line in the example I have been reading looks like this:

ON_REGISTERED_MESSAGE(UWM_U_R_ME, OnURMe)

but that causes a compiler error in BCB 4.0, undefined funtion. Can 
anybody tell me how to map correctly a Registered Windows Message?

The full problem is to keep the instances of an MDI application to one 
but still open as new child windows any files that may be clicked on by 
the user. If anyone knows the source of any example of this, then that 
would be much appreciated.

As always, all suggestions gratefully received.