function changeSelectionState(form, newState) {
    var offset = 0;
    for(offset=0; offset<form.length;offset++){
        if(form[offset].type == 'checkbox' && form[offset].id.match(/^ss/) ){
            form[offset].checked = newState;
        }
    }
}

function changeSelectionStateAll() {
    var form = document.getElementById( 'advanced_search' );
    changeSelectionState(form,1);
}

function changeSelectionStateNone() {
    var form = document.getElementById( 'advanced_search' );
    changeSelectionState(form,0);
}

function initChangeSelectonState () {
    var ssbutton1 = document.getElementById( 'checkssall' );
    ssbutton1.onclick = changeSelectionStateAll;
    var ssbutton2 = document.getElementById( 'checkssnone' );
    ssbutton2.onclick = changeSelectionStateNone;
}

addLoadEvent(initChangeSelectonState);