[NTG-context] variable edef with localhsize calculation

Dear All, I try to save \localhsize in a variable (with \edef), but whenever the enclosure changes, my variable changes too. \starttext \edef\myVar{\dimexpr (\localhsize-15pt)\relax} localhsize: \the\dimexpr\localhsize\relax \\ myVar: \the\dimexpr\myVar\relax \\ \setupnarrower[middle=50mm] \startnarrower localhsize: \the\dimexpr\localhsize\relax \\ myVar: \the\dimexpr\myVar\relax \\ \stopnarrower \stoptext I would expect that myVar has the same value inside the narrower as outside, because I used \edef and not \def. Is there another variable I can use, or does someone knows a solution for this specific problem? Thanks, Julian btw. everything works as expected, if I do not use \localhsize.