jQuery.fn.tooltip = function(options) {
    var options = jQuery.extend({
        txt: '',
        maxWidth: 300,
        effect: 'fadeIn',
        duration: 300
    },options);

    var helper,effect={},el_tips={};
    if(!$("div.tooltip").length)
    $(function() {helper = $('<div class="tooltip"></div>').appendTo(document.body).hide();});
    else helper = $("div.tooltip").hide();

    effect.show = options.effect;
    switch(options.effect) {
        case 'fadeIn':      effect.hide = 'fadeOut';    break;
        case 'show':        effect.hide = 'hide';       break;
        case 'slideDown':   effect.hide = 'slideUp';    break;
        default:        effect.hide = 'fadeOut';    break;
    }

    return this.each(function() {
        if(options.txt) el_tips[$.data(this)] = options.txt;
            else el_tips[$.data(this)] = this.title;
            this.title = '';
            this.alt = '';
        }).mouseover(
            function () {
                if(el_tips[$.data(this)] != '') {
                    helper.css('width','');
                    helper.html(el_tips[$.data(this)]);
                    if(helper.width() > options.maxWidth) helper.width(options.maxWidth);
                    eval('helper.'+effect.show+'('+options.duration+')');
                    $(this).bind('mousemove', update);
                }
            }
        ).mouseout(
            function () {
                $(this).unbind('mousemove', update);
                eval('helper.'+effect.hide+'('+options.duration+')');
            }
        );


        function update(e) {
            if (e.pageX + helper.width() + 40 > $(document).scrollLeft() + window.screen.availWidth)
            helper.css({left: e.pageX - helper.width() - 25 + "px"});
            else helper.css({left: e.pageX + 5 + "px"});

            if (e.pageY - helper.height() - 25 < $(document).scrollTop()) helper.css({top: e.pageY + 25 + "px"});
            else helper.css({top: e.pageY - helper.height() - 25 + "px"});
        };
};