Hello Harry Preiß,

I have been looking into your issue and I believe I have come up with a solution that can help you achieve the functionality you are looking for.

You could use the Infragistics.Windows.Utilities class to get the elements from the visual tree of a control. I have prepared a sample application for you in which you can see the using of Utilities.GetDescendantFromType method that can return the needed visual element. In addition, GetBoundsRelativeTo method is implemented that gives the possibility to get the relative location of any element based on a parent element, in this case, the XamGantt. Please keep in mind that the first returned row is actually the row with the headers.

Please take a look at the sample and let me know if you have any questions.