There appears to be an inconsistency in the way the forum handles a warning that a message being composed may be lost.
Consider composing a message which is not yet posted.
If I click something else on the site, such as the Forum, New Posts button, or even a previous message in that thread's index list, the software gives me a warning box with:
"This page is asking you to confirm that you want to leave - data you have entered may not be saved." with buttons 'Leave page' and 'Stay on page'
However, there are several operations that eliminate this warning making it easy to unintentionally lose the composed but unposted message.
The worst one (and most likely to happen) is to preview the message. A click on the 'Go Advanced' button disables the "leave page" warning from there on.
The same thing happens if you click the 'Preview Post' button while starting a new thread with the '+Post New Thread' button .
These actions, and at least one other way I found, can cause a user to lose all the (possibly carefully) composed text. By the time it is discovered, the back button may no longer recover the page. It would be helpful if the warning would be flagged for all circumstances.
If this can be added within the restraints of existing software, great. If not, then perhaps it could be sugggested for the future.