我发现 XeLaTeX 下的 microtype 和 Hoefler Text 存在奇怪的间距问题。下面提供了一个最小示例。使用 xelatex 排版时，“he”一词和强调的“ought”一词重叠，如下所示：
如果我使用不同的字体（例如 Palatino），或者删除 microtype 包，甚至删除第一句话，问题就会消失。任何有关导致此问题的原因的见解都将不胜感激。
\documentclass{article}
\usepackage{microtype}
\usepackage{fontspec}
\setmainfont{Hoefler Text}
\begin{document}
For some cause, which I could not at the moment divine,
Arthur was unusually grave and silent during our walk home.
It could not be connected with Eric Lindon, I thought, as he
had for some days been away in London: so that, having Lady
Muriel almost ‘all to himself’—for \emph{I} was only too
glad to hear those two conversing, to have any wish to
intrude any remarks of my own—he \emph{ought},
theoretically, to have been specially radiant and contented
with life.
\end{document}
参考更新：我正在使用 TeX Live 2013、microtype（2.5a）和 XeLaTeX（0.9999.3）的当前版本，如下面的问题所述。