Frameset Proxy Problem

How it was found

I was testing out the proxy pages (http://fct.li, http://staging.fct.li) and I found that if I create an HTML page with a frameset (not to be confused with iframe), then I would be able to get rid of the dialog (top right corner) that reads: "You're looking at this page through Factlink (visit original page)". So the page looks like its completely hosted by you guys.

Example (frameset): http://fct.li/?url=http://zenzr.org/fl-frameset.html http://staging.fct.li/?url=http://zenzr.org/fl-frameset.html

This is the source code for a frameset:

A hacker could easily create a phishing page and steal the user's credentials.