The spacing between fr
, fq
and ft
are all just normal spaces, because fr
, fq
and ft
are just normal character styles. What should work is to put a hook that gets triggered at the start or end of relevant style, eg insert into ptxprint-mods.tex
(advanced menu):
\sethook{end}{fr}{\MSPACE}
will make an (additional) M-space (probably too big) appear after every \fr
Options are you could use instead are:
\MSPACE 1em
\NSPACE - a normal space
\THREEPEREMSPACE .333em
\FOURPEREMSPACE .25em
\SIXPEREMSPACE .1666em
\THINSPACE .2em stretching or shrinking by 0.1em
\hskip 0.2em % rigid 0.2 em space
\hskip 3pt % rigid 3pt space
\hskip 0.3em plus 0.25em minus 0.2em % or whatever else you like.