Notice the tiny Retriev... image in front of this post in that screenshot?
That's the Retrieve account dialog... and there's no way I can resize it. :|
Interestingly, clicking Retrieve Lost Account again after cancelling the dialog now shows it correctly... but perhaps there's an issue that needs to be looked into there?
I don't know if it's reproducable, but I thought I should bring it up, just in case.
OS: Linux Mint 14 Nadia, with Cinnamon.
Edit: I'm unable to reproduce it after restarting Steam and going through the process. It seems to work correctly now, as if it needed to be clicked and cancelled in order for it to resize itself accordingly... though I know I won't ever receive the e-mail for verification so long as my domain remains in redemption status until I renew it on Jan 2nd... hence the attempt to change the e-mail. Unfortunately... Steam Support has yet to respond to me, so... I decided to try this route and encountered that.