Warning message when closing a new thread or new post page.

[Derek12]

First sorry if this was asked I couldn't find none similar

Might be a bit fool but In my experience I often accidentally close the tab or the browser (or if it or the entire system crashes during the reply) with the message half or full written because I am doing another things together then I lost all writing and if it is a long thread or reply is very annoying. Could you implement some warning message similar to Hotmail when you close the new email page tab

or better, some autosaving feature similar to this script that can recover even if the browser or the entire computer closes or crashes

Many thanks