I dont think we ever paid attention to how those buttons work or used them before. I just tested it with this post and, as I'm already logged into Facebook, it simply gave me an embed-link status update page which then posted an update to my profile with a link to this page. Clicking that button doesnt have anything to do with you having to login or out of TFL - but evidently Facebook wants you to be logged in to your facebook account to post there - so evidently something about the way your browser is set up is not holding your account logged in (maybe go to Facebook and login and be sure you're logged in first?) - but we cant tell you much about how that works as we have nothing to do with how the facebook login thing functions.

ok thanks. its nto a big deal but was just trying to share a great site with friends by makeing a link for them to go to so they can find this one easily. thanks tho.

I've found that my StumbleUpon toolbar is easier to use when I want to post something to Facebook. And yes, you do need to be logged into your FB account in order to post anything. There is a Share button in the Stumble toolbar for FB and Twitter.