wt_csstooltip

To enable this feature thre changes are required:

1. change line 72 in class.tx_wtcsstooltip_replace.php:
$this->description = ($this->conf['description2ascii'] == 1 ? $this->div->toascii($this->tips[$i]['description']) : $this->pi_RTEcssText($this->tips[$i]['description'])); // change to ascii signs?

$this->pi_RTEcssText renders the links that are defined in the tooltip definitions.

2. change the template file wt_csstooltip/files/templates/tooltip.html, e.g.:
<!-- ###TEMPLATE_TOOLTIP### begin -->
<span class="wt_csstooltip"><a href="###LINK###" ###JS###>###SEARCHTERM###</a><span class="tooltip">###DESCRIPTION###</span></span>
<!-- ###TEMPLATE_TOOLTIP### end -->

3. change css file typo3conf/ext/wt_csstooltip/files/css/default_wtcsstooltip.css e.g.:
.wt_csstooltip a {
position: relative;
z-index: 240;
color: #3E3E3E;
}

.wt_csstooltip a:hover {
z-index: 250;
text-decoration: none;
background-color: #eee;
}
.wt_csstooltip .tooltip {
display: none;
z-index: 250;
}

.wt_csstooltip:hover .tooltip b {
font-weight: bold;
font-size: 12px;
}
.wt_csstooltip:hover .tooltip {
display: block;
position: absolute;
margin-top: -1px;
margin-left: 2em;
width: 250px;
height: auto;
overflow: hidden;
font-size: 11px;
color: #666;
background-color: #ffe;
z-index: 999999;
padding: 5px;
}

Of course the template and css files are just examples what could work.

This settings work for me with Typo3 4.2.6, Templavoila, Realurl