Table Header Last Line of Page

["Jack Fitzpatrick" <jfitzpatrick@xxxxxxxxxx>]

How do you prevent table headers from being the last line of a page?  My
tables are constructed  strictly to the HTML4 model with a "thead" element,
followed by one or more "tbody" elements.  The table construction is quite
simple, with a table-part flow object consisting of a header port and
principal port.  This causes the header row to be carried over on page
breaks, which is desired.  However it is possible to get a table header row
as the last line of a page, even when the entire table is specified as keep:
'page.  I tried constructing thead and tbody as display groups instead of
sequences and specifying keep-with-next?: #t, but this has no effect.  Any
suggestions?  I'm using Jade v1.1 with RTF.

(element table
    (make table
        (make table-part
            content-map: '((thead header) (tbody #f)))))

(element thead
    (make sequence
         label: 'thead))

(element tbody
    (make sequence
         label: 'tbody))

BEGIN:VCARD
VERSION:2.1
N:Fitzpatrick;Jack
FN:Jack Fitzpatrick
EMAIL;PREF;INTERNET:jfitzpatrick@xxxxxxxxxx
REV:19990422T005213Z
END:VCARD