Most forums and many websites (like gmail) are able to save your post in a cookie as you type. If you navigate away by mistake, the post will be waiting for you if you go right back.
Does the billion dollar forum have that feature? I got so used to it I forgot this forum is so old... :/
It happened to me a couple of times while writing a post, my computer restarted due to a power outage. After rebooting, the text I entered was still there. No special cache settings. (Chrome browser)
Also, the preview button saves the currently written post into a draft and is available there for 7 days. It seems to me that this is quite enough from the "outdated" version of the software.