Place a heading at the top of a page on the grid

In the following example the first heading should be placed on the second grid line while the space between "Heading" and "Subheading" should remain as is. Interestingly, the grid options high, low and box yield the same result as none (in setuphead[section]). All other options from the "It’s in the details" manual move the heading down a line as desired, but also affect the spacing between the headings.

setuplayout[grid=yes]

showgrid

setupwhitespace[line]

setuphead
    [section]
    [style=bfc,
     before=,
     after=,
     grid=none]
setuphead
    [subsection]
    [style=bfb,
     before=,
     after=,
     grid=none]


starttext

startsection[title={Heading}]

startsubsection[title={Subheading}]

input ward

input ward

stopsubsection

stopsection

stoptext

How can I solve this?