Firefox: How to get your Menu back after you hide everything

Firefox 3 stores its session data in a JavaScript file located in the user profile folder. To restore an accidentally discarded session, simply:

1. Quit Firefox.
2. Replace the current JavaScript file with the backed-up version.
3. Restart Firefox.

—Jesse Kirdahy-Scalia (13 September 2009). "Restore a Lost or Discarded Firefox Session in Three Quick Steps". Open Media Boston. Media Working Group, Inc.

I also use that plugin and I use the Session Manager plugin for this exact purpose. When I'm developing I often end up with a load of tabs about a particular thing and want to store them in the same tab tree order, but wouldn't want to bookmark them. I'd have tons of unwanted bookmarks.

I just save the window as a backup session and give it a relevant name, and category if required, and then when I want to retrieve them just load the session. It closes all the other tabs and opens the backup session.

I know you say you don't want to store the session, but from your description its ability to store the tab tree is just what you're looking for?