I think it should work in the same way as in textbox (in which I don't know how it is implemented ), so you shouls allow for 2-3 pixels on each side , or half the font width, something like that.
I didn't think about vertical alignment - I believe ther the padding is enough.
Another problem:
The clicking on the device for activating an item requires a very hard tick. is it possible to play with the sensitivity of it ? I guess you control the difference between a click and a touch for moving the list.
Edit: I checked again and found that the click on the device just needs to stay a little bit longer on the item in order to activate it smoothly. No need to change anything.
