I am not sure what to make of this new feature. On one hand, I am finding it very annoying that when I open a thread, if my mouse pointer accidentally crosses a particular region of the screen on its way to somewhere else, a great big box appears and obscured everything beneath it. It may be bigger on my computer as I use Firefox with the text enlarged so I can read without having to be too close to the screen, but that doesn't make a pop up less annoying.

As for the "sharing", I am not on the various networking sites, so cannot really assess if the idea is worth trying. My one specific misgiving comes down to the ease of clicking a box, or, as happened to me yesterday, the ease of ACCIDENTALLY clicking a box, and as a result a thread exploding out through cyberspace. We have often had comments from mudcatters that specific postings have been made in the heat of a thread, and when looked at later, they wish they had held off and not typed their comment. This clicking seems to me just too easy.
There will be the puffed up self-important poster, who thinks the world should be inflicted with any comment they make, however trite, offensive or vacuous. There will be some enthusiastic newbie who just clicks on EVERY thread, flooding the internet with stuff that ought to be allowed to disappear.
If you make the sharing just a bit more effort, then people would think before sharing, and as a result, only share the threads which they believe have sufficient value.

Quack!
GtD.