Create a floating Feedback button for website in Javascript

Hello, I would like to add a floating FEEDBACK button to my website, like the ones used on Uservoice.com. You will need to code this in javascript. If you need to use any libraries, then Prototype and Scriptaculous are allowed. You do NOT need to design the button, that will be done by me. Features needed: -Code that can be added in a template file, so it appears on every page and works in all modern browsers -The feedback button always floats, and the position can be set inside the code, and changed if needed (top left/right, bottom left/right, middle left/right or absolute/relative position) -When the button is clicked by the user, a comment/feedback form will pop-up (as a lightbox or overlay on the same page), and the user will be able to leave feedback there, which is mailed to both website admin and a copy to the user. I need to be able to modify(add/remove) feedback fields as needed, but the starting ones should be Name, email and feedback. -If they have not provided feedback already, they will be asked to do so when leaving the site (need to be able to turn this off, if needed, and optionally - adjust the amount of visitors that are asked to leave feedback in percent) Thank you!