We have to admin this proeprty cannot be used successfully in RadTreeView and we will remove this setting from this demo. When TouchDragTrigger is set , the DragDropManager sets additional element on top of the RadTreeView and that is why MouseDown and MouseDoubleClick events are not propagated to the RadTreeView.
Currently there is no easy way to change the touch drag trigger in RadTreeView but we have a feature request that you can vote for
As for the RadList you mention - is it RadListBox or RadTileList or RadTileView ? In the RadListBox DragDrop Demo
the Selection works correctly on touch devices and the TouchDragTrigger is TapAndHold.
However, please keep in mind that this proeprty is set on the ListBoxDragDropBehavior.
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