Hello Juergen Holzer,
Thank you for contacting us.
RadListControl does not support this mode. However, you can set the AngleTransform property of RadListElement to 90 degrees (refer to the attached screenshot) and after that, you should set the visibility of the vertical scroll bar on FormShown event. To do this, set the Visibility to Collapsed through the Edit UI Elements dialog and copy the serialized code from the InitializeComponent method to FormShown.
I hope this helps.
the Telerik team
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