jquery home page...what is this type of effect called, and where can i learn more about this type of effect?

jquery home page...what is this type of effect called, and where can i learn more about this type of effect?

hello,

first off, let me say that this jquery site itself is gorgeous.  seriously excellent.

that being said, on the front page (http://jquery.com/)  there is a white box in the lower left hand corner with some code, and then it says "Run Code" in a gray box to show you how it works.

I thought it was completely cool.

I was wondering:
1) what is this type of effect called in the jquery world?  ("expanding box"?  "drawer opener"?)
2) where on jquery is this specific class of effect discussed in more detail?

I would really like to be able to do this effect: if you mouse over the box, the new text appears just like the jquery home page demo is doing, and then when you move the mouse away it disappears.  i'm not sure how to do that.  the way the demo is set up, the newly-appearing text box stays there forever unless you refresh the screen.

I'm very interested in the box overlapping whatever it is expanding over, and then disappearing back to just the box when the mouse is moved away.  That way it doesn't need a box of blank space to expand.  It will simply float over the existing stuff, and then go back away.  I think that would involve a CSS z index, but I'm not sure.

I saw some things like .fadeIn() and .slideDown(), but I think these will shove whatever is there down the page.  I want the box that is appearing to overlap the existing page.  Kind of like if you placed a piece of paper on a table.  It wouldn't move the table.  It would be on top and that part of the table would temporarily be invisible until the paper is taken away.

thanks!