WHY UNWANTED REFRESHING OF FACEBOOK?

[StevenCee]

Only since this latest update, and only on Firefox (desktop) does Facebook refresh itself every time I even glance away! Even FB gives a warning when actually leaving the page, that any data or changes we entered will not be saved. Firefox gives no such warning, so yes, I've lost, not only the thread I was in the middle of reading, but a quite lengthy comment I had composed, and was just about to add a quote, and post, also vanished! What is going on here, why is this mess happening???  I don't dare even look up from my keyboard, and see Facebook's page refreshing, for no reason, whatsoever!

[StevenCee]

OK, I see it's not just Facebook, but every tab that goes to sleep, & often blank, until woken up. However, while this can be an inconvenience on some other sites, it never did this before with Facebook, where it is a major nuisance. Is there any way to either turn off the setting for individual pages, or lengthen the time before it puts itself to sleep?  Oh, and this feature doesn't always seem to operate the same way with every open tab, as another discussion group I had open for at least half an hour, is still where I left it, and did not refresh when I came back.