My plan to combat this in any future interviews (and a couple of previous ones) is to bring my laptop with me. If there's any development questions, I'll do it on my laptop. If they become offended that I want to develop in my preferred environment, on my preferred keyboard layout (Dvorak + capslock->backspace), with my preferred editor... they have failed my interview. It ought to be a plus that I came that well prepared.

Incidentally, having been on the interviewing side, I do not see this often enough. Bringing your own laptop ought to be something you always do. I can provide "a" coding environment but it won't be "yours". Unless you always develop in a completely uncustomized standard Visual Studio environment, maybe (in which case frankly I'm still wondering a bit...).

My first action on a new machine is:

  git clone $myserveraddy/homedirpublic .  

which includes a relevant vimrc. Helps alot. (get permission first with explanation of why...)

This gets even more embarrassing if you're used to typing in dvorak. I can never remember the actual keys I use to perform certain actions - my fingers obviously know how, but my brain has no longer retained the actual mapping. And I can't just look down at the keyboard to figure out which key it is, since I don't have a dvorak keyboard, just remapped the qwerty one to use the dvorak layout.

I've remapped caps lock to ctrl on my personal laptop, so whenever I use another computer, I end up typing half of my commands / text in uppercase.