[VM] how to display text/html body part on request?

[juha . heinanen]

Sometimes I receive "multipart/alternative" messages, where "text/plain" part 
is either empty or tells to read the message using an html capable mail reader. 
Here is an example of vm-list-mime-part-structure on such a message:

("multipart/alternative" "boundary=----=_Part_8316_1598440439.1540713452805")
 ("text/plain" "charset=UTF-8")
 ("text/html" "charset=UTF-8")

How can I in such a situation tell vm to display the "text/html" part?  I don't 
want to see the "text/html" part automatically for every message, but only if I 
have to.

-- Juha