Collapsed borders paint a shared edge once, so the spacer <tr> bridging
the gap took the row separator with it and left one fragment open —
visible in a fixture as tables missing their frame on a page. The spacer now
draws the line LibreOffice draws there: the separator the break falls on,
or the table's own box where the rows carry none. Absolutely positioned,
since a collapsed border on the spacer shifts every row below by half.
Steffen Becker
2803e6196e