The DHTML client supports Tooltips since Version 7.
In charts they are supported in IE only when there is a tooltip for the whole object. In other browsers like Firefox, Safari and Chrome for example the tooltips on columns will show, too.
Tooltips will only show if the browser is the active window. This is true for all browsers.
On mobile devices the tooltips will not show.
If you are experiencing the missing Tooltipp only when the chart is using a non flat style, despite the browser having focus, you should contact our support directly.