Embedding a DirectX application into another windows application

Hi everyone!

I am just faced with a pretty strange problem. I have to embed an existing, stand-alone application's window into another application's window.

Let me explain: There is a DirectX application (more exactly a windows client application that uses DirectX to display a GUI). I want to write another windows application (C++) that has its own GUI. This C++ application should include the DirectX application in its window like a passepartout surrounds a picture.

I know that something similar can be done using COM objects (e.g. embedding an Adobe PDF viewer into an application). However the DirectX application doesn't come with any libs for that purpose. I also can't modify the DirectX application and there are no special interfaces.

So I am looking for a totally generic way to start any (DirectX-)application executable by my passepartout application and embed the DirectX-output-window into the passpartout-window.

There needs to be no further communication between the two applications in the first instance.

I have no idea where to start so I would be very happy about each hint! Thanx in advance!