new earth online

As I've mentioned in a previous post, and as you may have noticed from using it - IE8 has a button to switch the browser into IE7 rendering mode with just the click of a button. Definitely a useful feature if you're a developer or designer as you can test your design in IE7 and IE8 in the same browser window. I do wonder if they will keep that button there in the final version, or if they'll move it to somewhere else. From a developers point of view it kind of feels like they'd be doing something like:

if (IE7Button.state) {
   ...
}
else {
   switch (viewport.doctype) {
      ...
   }
}

Although that probably isn't how they're doing it, it kind of gives an idea of how the rendering engine probably switches "under-the-hood". What would be kind of cool is if they decided to also include the rendering engine from IE6 - true it'd add a little bloat to the browser, but if they did that just for an IE8 "Developer only" version it would still be very useful and very cool. It would mean that developers and designers alike wouldn't need to install a virtual machine running XP, or a second machine in order to test their sites in IE6 and IE7/8. If they did this I imagine it'd be either done from the "View" menu, or from a special IE8 web developer toolbar. Anyone else think it'd be a good idea for them to include other rendering engines too?