/* for switching css classes on tabs */
function switchTabs(element)
{
    var prefix = element.id.split('_')[0];
    var contentPrefix = arguments.length == 1 ? [prefix] : arguments[1];
    var index = 0;
    while((tab = document.getElementById (prefix+'_'+(index))) != null) {
		var current = tab.id == element.id;
        tab.className = tab.className.replace(current ? 'Off' : 'On', current ? 'On' : 'Off');
		for (var i = 0; i < contentPrefix.length; i++) {
            var content =  document.getElementById(contentPrefix[i]+'_'+index+'_content');
            content.style.display = current ? '' : 'none';
        }
        index++;
    }
}