Hi again,
After testing it out, turns out that defaultAlignment doesn't help much with anything at all regarding DataBox, probably why it isn't used anywhere
What does work to edit right-aligned numbers (e.g. currency, see extras/types/Currency.ec) or text, is creating a DataBox with 'autoSize' set to true, and anchor it to the right (anchor = { right = XX }).
With this it might be desirable to set the background color of the DataBox to the same as its background, and set borderStyle to none, so that it looks as though it is right aligned in a parent control (you may want to define an extra parent window with a deep border for it).
Cheers,
Jerome