TreeListBox Drag item but keep same depth

Hello,

We don't have a built in way to prevent dropping on items of different depth.  Your best bet would be to discover this scenario in your custom TreeListBoxItemAdapater's OnDragOver method and block dropping in that case via a "None" drop area, but also perhaps allow an "On" drop area when over a parent of the desired depth level.

If I insert this quick test logic in our TreeListBoxDragDrop QuickStart's OnDragOver method, it will block dropping on any target item that has an uppercase "R" in the name:

if ((targetItem is TreeNodeModel m) && (m.Name.Contains("R"))) {
	e.Effects = DragDropEffects.None;
	return TreeItemDropArea.None;
}

In your case, you'd want to make more complex logic that would calculate the depth of the item being dragged (firstItem) and the depth of the target item (targetItem).  If they don't match, use the "None" drop area result.  Or if the target is one level higher, use the "On" drop area result.