Hello Stanescu Mihai,
As I was able to understand you want only one Stack of Bars to be selectable on ItemClick. Here is how you can achieve this:
You may need to compare the XValue of the DataPoint and not the XCategory depending on your scenario. (marked in the code snippet with yellow).
Have in mind that
ChildrenOfType() method is extension method of
Telerik.Windows.Controls.dll so you will need to add reference to it.
Greetings,
Evgenia
the Telerik team