function activateResize(element) {
    Event.observe(element, 'keyup', function() {
      updateSize(element)
    });
    updateSize(element)
}

function updateSize(element) {
   //if scrollbars appear, make it bigger, unless it's bigger then the user's browser area.
    if(Element.getHeight(element)<$(element).scrollHeight&&Element.getHeight(element)<document.viewport.getHeight()) {
        $(element).style.height = $(element).getHeight()+20+'px'
        if(Element.getHeight(element)<$(element).scrollHeight) {
                window.setTimeout("updateSize('"+element+"')",5)
        }               
    }
}