Il my mailcap file, I have application/msword; antiword %s; copiousoutput If I try to download an word file witn Mozilla, it asks me if I want to open it with antiword, and then dumps the document on its standard output, usually ~/.xsession-errors. I think Mozilla shound take in account the copiousoutput flag, and recapture the output to display it itself.

Um... You're using a command that writes to standard output. You should be using "needsterminal" (not like we support that yet). I suppose we could make "copiousoutput" imply "needsterminal"... Past that, I'm not quite sure what a good way of dealing would be... There's no clean way to open "antiword | $PAGER" in a terminal window....

There is another way for Mozilla to handle copiousoutput : it can catch antiword output, and display it as a text/plain document. I think this would be the best way to do it, but it may not be trivial to do.

That would indeed be somewhat hard, and more to the point would be broken. Far too many apps that would be flagged with "copiousoutput" embed ANSI color/bold/whatever sequences in their output because they expect a terminal to handle it. Thus the output is in fact not text/plain and Mozilla's rendering of it would be pretty broken.