nice effect / widget

I came across this amazing thing I want to do the same on my website. Its from this link , the magics happens when you click on this button, does anyone knows how this can be done, or what is this effect / widget called so I can google for potentially solutions. thank you

Details from viewing site:

Clicking the

(Left Arrow Image) causes the left panel to collapse to a min开发者_运维技巧imal state (at which point the arrow changes direction and the process can be reversed)

UPDATE: How to position Left Arrow Image in that same place as in the website above, can I get some css hints ? thank you

UPDATE 2 : I'm currently using prototype for several functionalities on my website. thx

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It looks like they did it using mootools, but I think it's called a "slide" effect, and almost every javascript framework (prototype using scriptacouls, jQuery, etc.) has support to do that effect, and similar ones.

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you can google for feedback widget and come up with a variety of those .. also not incredibly difficult to build with jQuery's animate() function ..