[NTG-context] error with definestartstop and startmode

Hi, I get an "runaway error" with the following example: --8<---------------cut here---------------start------------->8--- \definestartstop[H][color=blue, before={\startmode[h]}, after={\stopmode}] \starttext test \startH TEST \stopH \stoptext --8<---------------cut here---------------end--------------->8--- How could I create such start-stop pair please? TIA for any hints, -- Peter