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JavaScript Gadgets'n'Gizmos
In order for the menu to work effectively you need to leave a border at the left of your page. This is no problem. Simply create a table with 2 columns, Make the left column wide enough to allow the menu to scroll without obscuring content then just put the content of your page in the right column of the table. I have made this page simple so you can view the source to understand what is going on. Also, here are the complete instructions on how to install this script.

To see how this script works, scroll down the page.

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