
\definetextbackground
  [underBar]
  [   location=text,
    framecolor=black,
   alternative=1,
       voffset=-.8\strutdp,
   background=,
         frame=off]

\starttext

Here is the start of the paragraph 
\startunderBar hello! (this looks fine) \stopunderBar{}
and some extra text running on to the next line

\blank

Here is the start of the paragraph 
\startunderBar \input ward \stopunderBar{} 
and some extra text running on to the next line

\stoptext
