How to remove x and y on submit in HTML form with Image type button?

You'll always get mouse co-ordinates for a submit button type="image"

You can use a standard submit type button and just apply styles to it to change the look.

<input type="submit" id="search-submit" value=""
    style="background-image: url(/images/search-button.gif); border: solid 0px #000000; width: WIDTHpx; height: HEIGHTpx;" />

They are the mouse coordinates of the click. I don't believe there's any way to prevent them - if you use an <input type='image'> then you get them. Why is it a problem? Can't you just ignore them?

Answering Prashant's comment: Digg are adding an onclick handler to the <input> (or possibly an onsubmit handler to the form) which builds the neat-looking search URL and redirects the browser to that URL, and then returns false to prevent the <input> from submitting the form itself. If you turn off JavaScript you'll see that you do get the x and y parameters in the URL. Clever!

document.getElementById("formid").submit = function() {
    location = "/search/?search=" + encodeURIComponent( document.getElementById("search-box").value );
    return false;
};