Honestly, I'd rather not click preview or "Go Advanced" because it defeats the point of the quick reply box. I'd rather be notified if someone else posted before I submitted my own post.
This isn't an idea because I'm sore about being ninja'd, just something I seriously think should be implemented, and have SEEN implemented on places all over the 'net. It's not that difficult and it's not even resource heavy since this can be done purely via JS, and it's so simple that even I could probably write the code myself if given the resources to do so. x3
To be honest I find being ninja'd as amusing as ever, but it does get a tad annoying if you're having a crummy day. :/
Do not belittle that, you know how immature some people can be.