[Guy Harris <guy@xxxxxxxxxx>]

> Eg, with, say an SMTP capture, one could stash the From: and To: address
> info in the conversation associated with a stream, and then it could be
> added to each frame as a hidden field, and filtered on.

Perhaps, instead, what you'd want is a way to say "show me all packets
that match this filter *AND* all other packets in the conversations to
which those packets belong", which means it'll work for *any* field - no
need to add it specially.