What do the tag box icons mean?

I've recently noticed that the box where you put the tags has some new icons. I already figured out one of them, but I don't quite understand the others.

On the box, there is a multi-directional arrow icon, a thumbtack icon, and an "emoticon" icon. I've figured out that the arrow icon allows the tagging box to hover in front of the picture that's being tagged, but that's all I've figured out. I don't understand what clicking the thumbtack icon does, and I'd appreciate explained to me what it does. Also, even if I put in the minimum amount of needed tags, the emoticon icon remains a red frown. What's the point of that icon, and what am I doing wrong?

The thumbtack icon pins your tag box so as you scroll through the page it moves along with the screen, the emoticon feature isn't bugged, it requires 25 tags before it becomes an orange "meh" emoticon, and then 35 tags before it becomes a green smiley.
It is also worth mentioning that it counts not only the general tags, but also the copyright, character, and meta tags.

thanks