I found a solution which is a little bit "dirty", not that kind I like, but it works! Now the tooltips could be styled as anyone likes.(until overlib_mini.js has been updated)
Insert at the end of /includes/js/overlib_mini.js
overlib_pagedefaults(WIDTH,250,VAUTO,RIGHT,AUTOSTATUSCAP, CSSCLASS,TEXTFONTCLASS,'jl-tips-font',FGCLASS,'jl-tips-fg',BGCLASS,'jl-tips-bg',CAPTIONFONTCLASS,'jl-tips-capfont', CLOSEFONTCLASS, 'jl-tips-closefont');
In your CSS-File:
.jl-tips-font {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 10px;
color: #000000;
}
.jl-tips-capfont {
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 10px;
font-weight: bold;
color: #000000;
padding-top:2px;
padding-bottom:2px;
}
.jl-tips-closefont {
font-family: Arial, sans-serif;
font-size: 12px;
font-weight: bold;
color: #730000;
text-align: right;
}
.jl-tips-closefont a, .jl-tips-closefont a:link, .jl-tips-closefont a:visited {
color: #730000;
}
.jl-tips-closefont a:hover {
color: #730000;
}
.jl-tips-fg {
background-color: #CCCCFF;
border: 1px solid #d0d0ca;
padding:15px;
}
.jl-tips-bg {
background:#333333;
border-left:1px solid #d0d0ca;
border-right:1px solid #d0d0ca;
border-top:1px solid #d0d0ca;
}
.jl-tips-button,.jl-tips-button:link,.jl-tips-button:visited,.jl-tips-hover
{
margin: 0px 0.5em 0.5em 0;
padding: 0;
white-space: nowrap;
text-align: center;
display: block;
width: 8em;
background:#333333;
font: bold 12px Menu, Arial, Verdana, sans-serif;
border: 1px solid #d0d0ca;
color: #404040;
text-decoration: none;
padding: 2px;
padding-left:5px;
padding-right:8px;
margin-top:10px;
}
.jl-tips-button:hover , .jl-tips-hover:hover {
background: #EEEEEE;
color: #000040;
text-decoration: none;
}