This is something annoying I've been going through recently. If the network fails for whatever reason while you are submitting a post, that post is gone forever and the message fields are wiped empty when you hit the back or reload buttons. You briefly see the message but then the message fields are blanked moments later.
I get there's a preview button for saving drafts, but what exactly is causing the post content to get cleared when you hit the back button? JavaScript? This does not happen with forms on most other sites, JS or no JS.
It's very annoying because the first post is always better than the next one; I had this problem several times before finding a solution. If you were about to submit and your connection went down, do not REFRESH the page because it will be blanked out permanently. Instead restore your connection, click on the broken url and it will take you to the blank comment box, then press the BACKWARD button to restore your post. This is the little trick i use.
