I'm looking at code for an old login form I'm redesigning. It's a simple table with two input fields for username and password.
But just before the end
</table> tag there's a blank iFrame which looks like
<iframe style="height:0px;width:0px;visibility:hidden" src="about:blank">This is a security measure.</iframe>
What possible security measures could this provide? I can't think of any and can't ask the guy who put it there in the first place.