I would like to be able to move elements in the navigator panel entirely by the keyboard.
Mouse dragging is extremely uncomfortable. Most programs containing a tree have shortcuts for pasting an element either as a child or a sibling. As far as I can see on http://help.webflow.com/keyboard-shortcuts there are no special shortcuts for arranging elements in the navigator panel.
The most convenient shortcuts I've seen so far are for this purpose are in the KeyNote tree-structured editor (https://code.google.com/p/keynote-nf/).