Currently only columns in first level of hierarchy trigger horizontal scroll bar when being expanded by width. The goal is when resizing columns deeper in the hierarchy to trigger scroll too.

<ClientSettings AllowDragToGroup="true">
<Resizing AllowColumnResize="true" AllowResizeToFit="true" EnableRealTimeResize="true" ClipCellContentOnResize="false" ResizeGridOnColumnResize="false"/>
<Scrolling AllowScroll="true" UseStaticHeaders="true"/>
</ClientSettings>