function advformupdate() {
    selector = document.getElementById ('addselect');
    if(selector.value == "forsale") {

        hiddenfield = document.getElementById ('addtype');
        hiddenfield.value = "forsale";

        divwrap = document.getElementById ('advwrap');
        divwrap.className = 'wraprentsale';    

        hide = document.getElementById ('rentonly');
        hide.style.visibility = 'hidden';
        hide.style.zIndex = 0;

        block = document.getElementById ('saleonly');
        block.style.visibility = 'visible';      
        block.style.zIndex = 10;

    } else {

        hiddenfield = document.getElementById ('addtype');
        hiddenfield.value = "forrent";

        divwrap = document.getElementById ('advwrap');
        divwrap.className = 'wraprentsale2';    

        hide = document.getElementById ('saleonly');
        hide.style.visibility = 'hidden';
        hide.style.zIndex = 0;

        block = document.getElementById ('rentonly');
        block.style.visibility = 'visible';
        block.style.zIndex = 10;

    }
}