btLr is not a writing mode that would be used by any natural language, the reason it makes sense to support this is that the Word UI makes it easy to rotate text 90 degrees counter-clockwise for Latin (lrtb) text, which then triggers this feature. This is common in the first column of tables to create text that looks like a row header.
An import-time workaround to handle
This commit just extends the sw core doc model, everything else is to be done in follow-up commits.
Change-Id: I89e02cd4b40de78699dbf14885fc128e870de3b8 Reviewed-on: https://gerrit.libreoffice.org/67717
db346dde6179 sw btlr wrting mode: implement document model
editeng/source/items/frmitems.cxx | 11 +++++++++++
include/editeng/frmdir.hxx | 5 ++++-
include/editeng/frmdiritem.hxx | 1 +
offapi/com/sun/star/text/WritingMode2.idl | 7 +++++++
4 files changed, 23 insertions(+), 1 deletion(-)