function start_ajax_loading(disable){
    if (typeof(disable) != 'undefined') {
        
        $(disable).addClass('ajax-loading')
        $$('#'+disable+' input, #'+disable+' textarea, #'+disable+' select').set('disabled','true');        
    }
    
    show_this($('loading_bar'));
}    
function stop_ajax_loading(enable){
    if (typeof(enable) != 'undefined') {
        $(enable).removeClass('ajax-loading')
        $$('#'+enable+' input, #'+enable+' textarea, #'+enable+' select').erase('disabled');        
    }    
    
    hide_this($('loading_bar'));
}   

function hide_this(el){
    el.addClass('nodisplay'); 
    return el;
}
function show_this(el){
    el.removeClass('nodisplay');
    return el;
}

function highlight_rows(rows){
    rows.addEvent('mouseenter', function() {
        this.addClass('hoverrow');
    });    
    rows.addEvent('mouseleave', function() {
        this.removeClass('hoverrow');
    });       
}