More reading:

We all know very well of the potential security holes present in Chromeless Windows. The idea behind this project is to push for a dialog screen that alerts the user that he/she is entering Chromeless Mode thereby averting any attacks, or malicious-intent inside a Chromeless Window.

Security:
Before Fullscreen got launched, there was a heated discussion on the possible security implications of Fullscreen. Couldn't attacker X just mimic a fake browser window, simulate a bank's login screen (address bar et al), and steal login info? Phishing does the exact same thing, but the URL is always cunningly disguised as the real URL. For example: http://bankofamerica.com.87654321.com/login.do. With an exact replica of the Operating System, as-well, as a browser mockup, it can be quite possible to mimic the real URL, so all the user sees is http://bankofamerica.com/login.do.

Putting the user in control:
When fullscreen got launched, obviously the Mozilla team did their homework. Firstly, the user knows very well they're entering fullscreen mode (via a very well placed message). As-well as this, the user always has to "click", or otherwise activate Fullscreen through a button. Click-jacking, however is out of the question with Fullscreen. (I've tried it). You can't fire-up Fullscreen by emulating a click. So with this in mind, Chromeless Windows should adapt the same pattern.

A history of chromless:
Chromeless windows are not new. Infact when IE6 got launched, Fullscreen APIs were already implemented in it. (These were known as Kiosk Mode windows). A very clever man named Gabriel Suchowolski was the first to exploit this feature, and he created the world's first, entirely browser-based Chromeless window. There was even a site called chromeless.org that showcased other people's variations of the hack. It was achieved by making a window fullscreen, and then resizing it. Any extra functionality, including dragging the window, resizing it, etc was all done with JS, and CSS.

Possible modern day Workarounds / hacks
We can create Chromeless windows relatively easy these days with Firefox Extensions, however the aim of this project is to persuade the browser vendors to enable this behavior by default, and have Chromeless functionality 'baked in' to the browser. We talk fervently about building Web Applications for the web without realizing what an Application is. An Application should give full control to the designer who builds it, as-well as the user. I agree with Remy Sharp when he says in this talk, that we should "make our apps more appy".