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JavaScript-FX
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.

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

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