display_filter and multipart mails

[mike9 at posteo.nl]

I receive mails from someone using Content-Type: multipart/alternative
with two parts. First: text/plain, second: text/html. The first part
is always buggy (missing blanks and incorrect paragraphs). This is why
in this case I like to display the second part.

It seems display_filter always receives the first part of an email.

How can I tell mutt to pass a certain part other than the first to
display_filter?

Mike