There are a couple issues the the sessions feature. First is if XnView is killed instead of exiting normally, no new save is created, so when it is restarted it opens the session from the last time it was exited normally. So if it, or Windows, crashes, or Windows restarts and XnView isn't shut down properly for some reason, any newly opened tabs will be lost. The second, and perhaps bigger, issue is that if any files that were open in a session and saved aren't available when XnView is run, they will simply be lost. This could be avoided either by a dialog to warn the user and give them an opportunity to cancel the loading of the session (and keeping the session saved and making it clear that XnView will do so) or to make the files available before continuing. An even better solution (either on its own or, ideally, in conjunction with the dialog box) would be to create a session metadata file and create a backup one when there's an issue loading any files, so the backup session can be reloaded once they're available. budz45 has some great ideas relating to these specific issues and other ways to improve the sessions feature here
, and it's unfortunate to see nothing has come from it after 4+ years. I would have posted there, instead of creating a new thread, but I didn't want to necro it. Feel free to merge this post into it if that's preferred. I just really think these are major flaws in an otherwise amazing system, and would love to see improvements made.