For Firefox, Session Restore came in version 2 back in 2006 - Wikipedia
I’m not sure when Internet Explorer added the feature, but they removed the automatic restore in version 8 and made it manual in 2009 - Wikipedia. I feel like Internet Explorer 6 had this feature, but I can’t remember now.
Not sure when/if older browsers like Netscape Navigator had this feature.
For Firefox, Session Restore came in version 2 back in 2006 - Wikipedia
I’m not sure when Internet Explorer added the feature, but they removed the automatic restore in version 8 and made it manual in 2009 - Wikipedia. I feel like Internet Explorer 6 had this feature, but I can’t remember now.
Not sure when/if older browsers like Netscape Navigator had this feature.
My “two decades” guess wasn’t too far from that, then.