So, there I was typing a long post into a text box on a webiste not unlike Perlmonks. I was not too familiar with their system to I clicked on Preview, spotted a mistake and immediately clicked Back to fix it. Doh! Where's my posting?

Annoying, yes... What I'm doing in Opera if I fill out a big form and I'm scared it could vanish, I click on "Create linked". The POST will appear in a newly opened tab, the original window still contains the filled out form.
still, this is just an unnerving workaround...