
The 'Recently Closed Windows' under History is greyed and only restores some of the closed windows on startup.
Yesterday I had 4 windows open in Firefox 47 but today when I started Firefox only 3 appeared and the 'Recently Closed Windows' under History is greyed so the 4th window won't open.
Yesterday I had 4 windows open in Firefox 47 but today when I started Firefox only 3 appeared and the 'Recently Closed Windows' under History is greyed so the 4th window won't open.