\documentclass[ngerman]{scrartcl}
\XeTeXtracingfonts=1

\usepackage{babel}
\usepackage{libertine}
%\usepackage{fontspec}
%\setmainfont[RawFeature=+ccmp;+locl;+mark;+mkmk;+kern;+liga;+clig;+trep;+tlig]{LinLibertine}
\usepackage[left=1cm,right=1cm,top=1cm,bottom=1cm,a4paper]{geometry}
\setlength{\parindent}{0pt}
\usepackage{eso-pic,calc,xcolor}

\makeatletter
\AddToShipoutPicture{%
  \begingroup
   \color{lightgray}
    \thinlines%
    \ESO@div{\paperwidth}{\ESO@gridDelta}%
    \multiput(0,\LenToUnit{\ESO@yoffsetII})(5,0){120}%
       {\ESO@Vline{\LenToUnit{\paperheight}}}%
  \endgroup
}
\makeatother

\begin{document}
\section{Kerning-Test: Linux Libertine: fxl-d-sl}

{\fontfamily{fxl}\fontseries{d}\fontshape{sl}\fontsize{3cm}{3.2cm}\selectfont
\input{testkerning.inc}
}


\end{document}