As a workaround, the ScrollingSettingsBehavior.ScrollStep attached property of the RadListBox control can be set to a value equal to that of the Height of the RadListBoxItems. Available in R3 2017 Official Release Version.
Hi, We are fixing that behavior, so the auto-scroll will work as expected in all themes with R3 2017 version of Telerik UI for WPF. However if you are using an ItemTemplate or custom Style that modifies somehow the Height of RadListBoxItem you would need to set the telerik:ScrollingSettingsBehavior.ScrollStep of RadListBox to the ActualHeight of RadListBoxItem. For example: <telerik:RadListBox telerik:ScrollingSettingsBehavior.ScrollStep="44" ... ></telerik:RadListBox> Regards, Kalin