How to detect mouse moving while left button down

Question

I want to use javascript to detect the mouse position once the mousedown event has fired. It appears I am not getting an onmousemove event when the left button is held down. The cursor is changing to some circle with a cross through it.

My whole goal is to detect the start position of the cursor on mousedown and change the top left style of a image in a div with overflow set (kind of fake pan effect).

Thanks

Answer 1

Set up an ondragstart handler:

function dragstart(ev)
{
    if (!ev) ev = window.event;
    ev.returnValue = false;
    return false;
}

image.ondragstart = dragstart;