Event.observe(window, 'load', function() {
    var $searchField = $('tsearchQ');
    if($searchField.value == '') {
        $searchField.previous('label').show();
    }
    
    Event.observe($searchField, 'focus', function() {
        this.previous('label').hide();
    });
    Event.observe($searchField, 'blur', function() {
        if (this.value == '') {
            this.previous('label').show();
        }
    });
});