Hi Lantu Datinh,
I strongly suggest you to not use UI virtual components like ListBox, DataGrid, RadGridView, etc. inside StackPanel, ScrollViewer, etc. This containers will measure with infinity which will case UI virtualization to create all elements for all data items - you may get huge performance problems. As to the grid hierarchical scrolling the approach I've suggested you is the only way to achieve your goal currently. RadGridView does not support something like hierarchical virtualization where only the root grid will have scrollbar.
the Telerik team
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