This is an old thread.  I still have the message in which there are
problems.

Lars sent out a five-part message which was supposed to be handled
correctly by Gnus.  Unfortunately, there were some funny things with the
text/html part.  Mainly, it looked like there were some missing EOL
characters, so that the text/html was concatenated onto the end of the
text/plain before it.

When I buttonize the message and whack the text/html part, it is not hidden
correctly.  When I whack it again, a copy of that part is added to the
buffer.

Here is an example: