Personas 2.0: How to exit an Personas app by pressing a button?

Hi Personas 2.0 experts,

I made a Personas app and now the client wants the following way of exit:

The client can presses an image on a webpage which will launch the url of the Personas app. After user has done his tasks inside the Personas app, he wants to press an button which will exit the Personas app and go back his original webpage. One can close the Personas app by closing teh Personas window, but the client wants to use a button (or script) to quit teh Personas.

Does anyone have an idea on how to do this? Thanks.

Br,

Dong