The 1x1 fixture carried an IDAT from a different image: its CRC fails and the
zlib stream is truncated. Chromium and WebKit render it anyway, Firefox reports
"Image corrupt or truncated", and the same bytes sat in eleven fixtures.
textBox becomes an inline node carrying block content, like the frame both
formats write, so "in line with text" really is in the line and a box reaches
a table cell or a list item through their paragraphs. Both exports write it
where it sits (an as-char draw:frame / a wp:inline drawing) and both imports
leave it there, which drops the hoisting machinery on either side.
Two guards the schema cannot express: no box inside a box, and a selection
reaching into a box grows to the box's bounds rather than dissolving it.