Using IE6 on Win XP with Flash 10, it is not possible to tab to the "Browse/Add More" button.
1) Open the template file in IE 6 on Windows XP with Flash 10 installed:
2) Try to tab to the "Browse" button
---> You can't
3) Use the mouse to add some files to the queue
2) Try to tab to the "Add More" button
---> You can't; focus will land on the queue and on the "Upload" button, but not the "Add more" button