As I'm reading the fontspec
manual it seems like I should be able to loosen the tracking of a line of type like this:
\documentclass[border=1mm]{standalone}
\usepackage{fontspec}
\addfontfeature{LetterSpace=50.0}
\begin{document}
Full fathom five thy father lies
\end{document}
but it doesn't work. What needs to change?