How Google makes ajax requests without invoking HttpRequest object

Firebug doesn't show any Ajax request being sent to Gmail when i delete any of my conversations. How they are doing i开发者_开发技巧t?

They do not use AJAX, they use iframes in most cases. For example I found they frenquently uses an iframe that points to this URL http://www.google.ch/blank.html and they uses to make the requests and retrieve the response data.

A bit archaic, but most safe (maybe).