[Dev-luatex] letter spacing in display math

Hello, using fonts with additional letter spacing does not seem to work in display formulae. (Not sure whether it's a bug in luatex or whether I should report it to luaotfload instead.) Example (LuaHBTeX, Version 1.15.0): \documentclass{minimal} \begin{document} \font\f="DejaVuSerif-Italic:letterspace=20.0" at 10pt \f % these work as expected \hfill abcdefxyz\hfill\hbox{} \hfill$\textfont1=\f abcdefxyz$\hfill\hbox{} \hfill$\textfont1=\f\displaystyle abcdefxyz$\hfill\hbox{} % these don't $$\textfont1=\f abcdefxyz$$ $$\textfont1=\f\textstyle abcdefxyz$$ \end{document} Am I missing something? Achim