When an element containing a reorderer is moved to a different width space, the keyboard movement in the inner reorderer is incorrect. It appears that when moving an item, it consistently skips over the adjacent item and moves the item two spaces instead of one.
To recreate use the uPortal mockup example that has a lightbox portlet.
1. Tab to the outer reorderer (the portlets)
2. Arrow to the lightbox portlet
3, Move the lightbox portlet to the other column
4. Tab to the inner reorderer (the thumbnails)
5. Move a thumbnail right.
6. Notice how the thumbnail moves over two spaces instead of one.