Import attached test page.
Open it with VPE. Select Visual/Source tab
In Visual part navigate elements using keyboard.

Next possible navigation problems found(navigation started from top):

1. Richtoolbar group (panel with 6 icons) - left-right on icons don't work
2. Datalist element - "up" button from it don't work
3. Add ajax... - "up" button don't work
4. PanelBar - "down" button don't work
5. Canon - "up" and "down" buttons don't work
6. Panel (under the Canon element) - "up" button don't work
7. Tab under DataGrid - "up" button don't work
8. Expences - don't work "left", "right" and partially "up" and "down" buttons
9. Drop down menu - "down" button don't work
10.Slider part - "down" button don't work, when it selected