Are you running the latest version 0.0.5-2 from extra-testing? Perhaps you should update and try it again.
You're currently able to delete all items at once and single items, too. Simply select a item from the List at the top and press the trash can Button.
It is going conform with the maemo design guidelines. You don't need the cursor keys (I must admit, I haven't tested it using the cursor keys myself) As soon as the list is long enought you can always scroll thru the list using a swipe gestue. To select a Item simply tap it.
Hmm... there is a cursor as soon as the text-box has the focus. But I'm sure. If you stop using the cursor keys to scroll thru the item list you won't need to see which has the focus. The N900 has anyway no tab button.
My applications are always selfmade! Otherwise I wouldn't publish those. So if everything works don't forget to vote