This post is in response to this 'not so recent thread' [webmasterworld.com
...] because I did not see the fix posted and had to do it myself.
There is an XSS issue with allowing an iFrame to control a parent window, so the iFrame must reference a relative URL.
Using the preceding, the following in the <body> tag of the iFrame should work in most major browsers. (AFAIK)
NOTE: This is currently being tested, so if anyone notices (or knows) of a necessary difference, please post, and I'll post again if there are issues noticed or it's necessary to make any changes, but currently it seems to be working well.
EDITED TO: window.parent.scroll(0,0); to be 'more correct'.