648081 - Add support for multiple session restore from History menu

Status: RESOLVED WONTFIX

(Firefox :: Session Restore, enhancement)

Description

[Ben]

User-Agent:       Mozilla/5.0 (Windows NT 5.1; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Windows NT 5.1; rv:2.0) Gecko/20100101 Firefox/4.0

Serious data loss issues exist in Firefox 4.0, both for people who haven't discovered the undocumented on-demand session restore - Bug 636777 - and those who have - Bug 637148, Bug 636716.

The severity of these and other related bugs could be greatly reduced by adding a basic form of multiple session restore, for instance by turning 'Restore Previous Session' on the History menu into a parent menu.  Example submenu items would be as follows:

  Session 1 (1 Window, 1 Tab, 1 Group)
  Session 2 (2 Windows, 53 Tabs, 2 Groups)

So if, in the example above, Session 1 was the instance of about:home from Bug 637148, the user could easily locate their main session, Session 2.  (The button on about:home would always restore Session 1.)

The menu would hold the last 5 or so sessions.  (Each session is just a small database of windows, tabs, tab order, favicons, etc, so has a small filesize.)  It would certainly be desirable to also have a way to delete individual sessions, but the primary issue here is of widespread data loss - potentially for tens of millions of users.  The solution here would alter that to data misplacement.

Note that selecting Session 2 in the above example would make it Session 1 - in other words, no sessions would be lost just by looking for the relevant session.  Exiting at this point would retain it as Session 1.  (By naming the session files sessionstore1.js, sessionstore2.js, etc, advanced users could delete an unwanted session with the browser closed; if sessionstore1.js was not found by Firefox on restart it would rename sessionstore2.js to 1 and so on.)

Bug 645554 suggests a way to opt out of a session restore on startup.  What would probably be more useful would be a way to escape from a session load already in progress, for instance by pressing the Escape key.  Tabs that were yet to partially load would be automatically closed, and partially loaded ones would be stopped from loading further.  Therefore, if the user had a couple of 10-tab sessions on the History menu they could quickly determine the important one, by halting it if wrong.  (Again, note that halting doesn't delete it; it would be retained as Session 1 - the most recently accessed.)

Multiple session support actually already exists in the program: It's possible to have nested instances of the about:sessionrestore tab saved, and these work correctly.  But while that sort of graphic user interface - which shows individual tab names with favicons - would be desirable, a basic submenu as above would be sufficient to avoid data loss in most cases.  Fancier solutions could be developed later.  But it's critically important to have some sort of solution _built into the browser_ (not in the form of an add-on) asap.

Reproducible: Always

Steps to Reproduce:
1. See relevant bugs.
Actual Results:  
Session is lost

Expected Results:  
Session is located

Comment 2

[Mike de Boer [:mikedeboer]]

We will not support restoring multiple sessions in the near future. This is very good add-on fodder.