[NTG-context] \typebuffer and tabs / specify code type

Hi all, I'm using \typebuffer to typeset some metapost code. How can I tell it to either ignore tabs or treat them like 1,2,3,... spaces, instead of printing ^^I? Another question: There has been a thread on telling \typebuffer what type of code on this list some time ago, without a final solution. Is there a switch to use metapost or whatever appropriate highlighting? Greetings, Eckhart