1524371 - Command "Restore Previous Session" is not accessible in some circumstances

Status: RESOLVED DUPLICATE of bug 1330638

(Firefox :: Session Restore, defect)

Description

[witrak]

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

Steps to reproduce:

I was working in a multi-desktop environment (Dexpot/Windows 7 64-bit) when saw the notification about Firefox new release (65.0). I decided to upgrade it, having a few FF windows open in another desktop (not visible at the moment).
When after attempted FF restart windows in the currently visible desktop disappeared but have not appeared again ("Wow! FF not started!"), I started FF by hand and realized that there's single empty window instead of two I had previously.
Knowing that it could be the result of the option "Restore Previous Session" unset, I checked it and decided that as the option was set, then something went wrong with the upgrade. After a quick search in Support pages, I found that I should use "Restore Previous Session" command in the main hamburger menu or in Tools traditional submenu.

Actual results:

Then I realized that there's no Restore Previous Session command in both menus.
After unsuccessful attempts to find an appropriate explanation on the Internet, I found the other open FF windows in another desktop, with all tabs restored.
However, I still couldn't understand why the Restore Previous Session isn't accessible nor visible. I spent some time trying to make the command visible, then found that it is displayed when in Firefox Options the option "Restore previous session" is not set.

Expected results:

That is extremely confusing.
Firstly, because there's no mention about it in the relevant menu description(s) and responses to questions on support.mozilla.org. and secondly, because in general, commands visibility shouldn't depend on specific state of an application (such commands could be greyed out instead).
Also, it means that there's no way easy way to restore the previous session if in fact something goes wrong and the session isn't restored correctly.
And finally, while I don't see any reason to disable this command at all (if all windows/tabs are already open, then execution should display informative message like "All Windows/Tabs are open already"), if really there are such reasons, then the command should be greyed out AND appropriate explanation should be available somewhere.
The rationale is simple:

• multi-desktop environments are common, so my mistake isn't improbable, and
• experienced users could use it to restore old sessions, manually backed up (by making copies of an appropriate directory - sessionbackups in case of Windows).

Comment 1

[witrak]

I don't think it is a software bug, but rather UX design and documentation bug. However, I've lost enough time because of it and think that it can be a source of frustration for many users. So definitely an improvement (in both parts of the excellent product: UI and docs) is worth to be considered.

Comment 2

[Mike de Boer [:mikedeboer]]

We already have quite a number of bugs filed that are aiming to improve the UX here over at bug 1330638, so that'd be a good place to look when we're ready to start addressing this.