There's a login form on page A: http://www.example.com/A.html
The 'action' attribute of which is: action="/B.html"
So when someone logs in with the form on A.html, the data will be submitted to / visitor redirected to B.html.
Now what I want is: there's an <iframe></iframe> on /C.html, framing B.html, is there any way so that when someone logs in with the form on A.html, the visitor is redirected to C.html and the login details is submitted to B.html that's framed on C.html in the <iframe></iframe>? So after the person logs in from A.html, he arrives at C.html with the actual CP dashboard framed in an <iframe>.