Scrolling in TabStrip does not work well when TabStripPlacement=Left or Bottom and ScrollMode=Item. Pressing the Scroll Buttons scrolls the entire set of tabs.
The fix is available in the R1 2018 Release.
Supporting tickets: http://www.telerik.com/account/support-tickets/view-ticket.aspx?threadid=505131 http://www.telerik.com/account/support-tickets/view-ticket.aspx?threadid=505135