Dear developers, Here is the example and warnings. Example: \startuseMPgraphic{mpos:par:columnset:textuline} \iftracepositions show_multi_pars \else draw_multi_pars \fi ; path p ; p := boundingbox currentpicture ; currentpicture := currentpicture shifted (0,-0.3*StrutDepth) ; setbounds currentpicture to p ; \stopuseMPgraphic \definetextbackground [underline] [location=text, alternative=1, mp=mpos:par:columnset:textuline, background=, frame=off] \starttext \underline{blurblur} \stoptext The compiled result has no underline and ConTeXt complains during compilation: mplib : making 'metafun.mp' into '/var/cache/texmf/luatex-cache/context/b51cb04348b3b14d1dfc7333fc9b63f2/formats/cont-en-metafun.mem' mplib : problems with 'metafun.mp' from '/var/cache/texmf/luatex-cache/context/b51cb04348b3b14d1dfc7333fc9b63f2/formats/cont-en-metafun.mem' Best wishes, Wei-Wei