I've never used a single-site browser, but I generally do make sure that my email is the only thing open when I'm visiting it (and clear private data to avoid anything weird in the cache beforehand).
Between that and noscript (and enough savvy to spot even slightly-wrong websites), I haven't had any problems. I don't think this attack would work on me because I've long kept email segregated from normal web browsing due to other attacks, which rely on you clicking malicious links while logged into the site they want to get your information from. So I would, if anything, just think I'd clicked on the wrong shortcut and close out of it rather than logging in. Score one for paranoia? I've never been infected by spyware/viruses/etc.
Between that and noscript (and enough savvy to spot even slightly-wrong websites), I haven't had any problems. I don't think this attack would work on me because I've long kept email segregated from normal web browsing due to other attacks, which rely on you clicking malicious links while logged into the site they want to get your information from. So I would, if anything, just think I'd clicked on the wrong shortcut and close out of it rather than logging in. Score one for paranoia? I've never been infected by spyware/viruses/etc.