How do I run another Android application/activity in a window inside my app

What I want to do is be able to start another Android sub application (which I have not written myself) to run inside a window within my main application. I would want certain touch events etc on the elements of the main app that are still visible to allow me to stop the sub application.

I've found examples of how to launch another activity using an Intent - but I have found nothing allowing me to specify that it runs in a certain window.

Is this 开发者_如何转开发possible at all?

The window metaphor does not exist under normal Android.

Some tablet makers have added it to their builds, but using windows would reduce the portability of your app.