Suppose you're using Firefox with lots of tabs open and then you do some software installations that necessitate multiple restarts.
After the first restart Firefox relaunches with a single empty window. At that point you could "restore previous session" but your mind is on other things.
You do the next restart and Firefox relaunches again, with a single empty window. This time the "restore previous session" option has gone, it's greyed out. DISASTER!!!
We can all see WHY this might happen. But it's NOT REALLY INTENDED BEHAVIOUR.
How about a fix??
- either, the "previous session" remains the last useful session, unless you start a new one, by browsing web pages in that empty window;
- OR, how about having, say, 5 "previous sessions' that appear in a list with a date/time against them. That way you can restore the one you want to and there's less chance of losing all your tabs.
Thanks!