I found a great post about using sharepoint tooltips on Andrey Markeev’s (@amarkeev, omlin) blog: JavaScript ToolTip’ы для SharePoint. He describes how he found the standard sharepoint tooltips and how they can be reused. The best part of it his “research”. Andrey’s conclusion is to create an own, simplified javascript class which enables “sharepoint” tooltips. I modified it somewhat. I think there is no need to instantiate a TooltipManager…

var Takana = window.Takana || {};
Takana.ToolTipManager = function () {

    var \_divId = "my\_tooltip";
    var \_innerDivId = "my\_tooltip\_inner";

    function createTitleAndDescriptionHtml(title, description) {
        return String.format(
            '<div>{0}</div><div>{1}</div>',
            title,
            description);
    }

    function showTooltip(element, rawHtml) {

        var tooltipDiv = $get(\_divId);
        if (tooltipDiv == null)
            tooltipDiv = createTooltip();

        $get(\_innerDivId).innerHTML = rawHtml;

        displayTooltipNextToElement(tooltipDiv, element);
    }

    function displayTooltipNextToElement(tooltipDiv, element) {

        tooltipDiv.style.display = '';
        var loc = Sys.UI.DomElement.getLocation(element);
        tooltipDiv.style.left = loc.x + 'px';
        tooltipDiv.style.top = loc.y + element.offsetHeight + 2 + 'px';

        if (tooltipDiv.curTimeout != null)
            clearTimeout(tooltipDiv.curTimeout);
    }

    function createTooltip() {
        var mainDiv = document.createElement('span')
        mainDiv.id = \_divId;
        mainDiv.className = 'ms-cui-tooltip';
        mainDiv.style.width = 'auto';
        mainDiv.style.position = 'absolute';

        var bodyDiv = document.createElement('div');
        bodyDiv.className = 'ms-cui-tooltip-body';
        bodyDiv.style.width = 'auto';

        var innerDiv = document.createElement('div');
        innerDiv.id = \_innerDivId;
        innerDiv.className = 'ms-cui-tooltip-glow';
        innerDiv.style.width = 'auto';

        bodyDiv.appendChild(innerDiv);

        mainDiv.appendChild(bodyDiv);

        document.body.appendChild(mainDiv);

        return mainDiv;
    }
    function hideDiv() {
        $get(\_divId).style.display = 'none';
    }

    var manager = {};
    manager.attachToolTip = function (element, title, description) {
        $addHandler(element, 'mouseover', function (e) { 
            showTooltip(element, createTitleAndDescriptionHtml(title, description)); 
        });
        $addHandler(element, 'mouseout', hideDiv);
    }

    manager.attachToolTipRaw = function (element, rawHtml) {
        $addHandler(element, 'mouseover', function (e) { 
            showTooltip(element, rawHtml); 
        });
        $addHandler(element, 'mouseout', hideDiv);
    }
    return manager;
}();

Now a manager is created on a page per default. To add a tooltip, just use the TooltipManager: