Table break with grid and dy != 0

[pgundlach]

<Layout xmlns="urn:speedata.de:2009/publisher/en"
  xmlns:sd="urn:speedata:2009/publisher/functions/en">

  <SetGrid nx="12" ny="12" dx="0mm" dy="6mm" />
  <Trace grid="yes" objects="yes" gridallocation="yes" />

  <Pagetype name="t" test="true()">
    <Margin left="20mm" right="12mm" top="12mm" bottom="23mm" />
    <PositioningArea name="article_main">
      <PositioningFrame column="1" row="1" height="12" width="12" />
    </PositioningArea>
  </Pagetype>

  <Record element="data">
    <PlaceObject >
      <Table width="12">
        <Loop select="3">
          <Tr>
            <Td padding-top="5mm">
              <Box height="3" width="3" backgroundcolor="rebeccapurple" />
            </Td>
          </Tr>
        </Loop>
      </Table>
    </PlaceObject>
  </Record>
</Layout>