Strange behavior when draggable div floats on the right

Strange behavior when draggable div floats on the right

Hello,
I would ask you if there is a reason for which, if I use:

  1. "right": "0",

at 55th row of javascript code of this demo (like at 45th row), it doesn't work, whereas, if I write in that way:

  1. "left": $('body').width() - $(this).outerWidth()

it works as expected.

Thanks a lot,
Cheers,

Riccardo