 default drag drop mode shows an insert mark at the point you are going to place
the node you are dragging.  This lets you either re-order nodes within a tree or
change their parent, and hence is useful in applications where the order of items
is important.
</li><li><span class="code">etvwDropHighlight</span><br />
Drop-highlighting nodes is a more familiar drag-drop mode which is used in the
Folder pane in Explorer.  This mode allows you to change the parent of an item
but not to change the order of the it