How can I get a fixed-position menu like slashdot's comment filtration menu

Question

Slashdot has a little widget that allows you to tweak your comment threshold to filter out down-modded comments. It will be in one place if you scroll to the top of the pag

Answer 1

Thanks for the effort of sharing this code. I made some small changes to make it work with the current release of Prototype.

var TableHeaderManager = Class.create({
    initialize: function initialize(headerElt) {
        this.tableHeader = $(headerElt);
        this.homePosn = { x: this.tableHeader.cumulativeOffset()[0], y: this.tableHeader.cumulativeOffset()[1] };
        Event.observe(window, 'scroll', this.handleScroll.bind(this));
        this.handleScroll();
    },
    handleScroll: function handleScroll() {
        this.scrollOffset = document.viewport.getScrollOffsets().top;
        if (this.scrollOffset > this.homePosn.y) {
            this.tableHeader.style.position = 'fixed';
            this.tableHeader.style.top = 0;
            this.tableHeader.style.left = this.homePosn.x;
        } else {
            this.tableHeader.style.position = 'absolute';
            this.tableHeader.style.top = null;
            this.tableHeader.style.left = null;
        }
    }
});