[NTG-context] MkIV: \processbetween and command with optional argument

Hi, LuaTeX hangs in the following example, it is related to the optional argument for \startTEST. \def\startTEST {\dosingleempty\dostartTEST} \long\def\dostartTEST[#1]#2\stopTEST {\bgroup \processaction [#1] [bold=>\bf, italic=>\it unknown=>\tf]% #2% \egroup} \def\TEST#1% {\startTEST#1\stopTEST} \def\defineTEST[#1]% {\processbetween{#1}{\TEST}} \defineTEST[MYTEST] \starttext \startMYTEST text \stopMYTEST \startMYTEST[bold] text \stopMYTEST \stoptext Greetings, Wolfgang