This is an umbrella bug for the refactoring steps. It's about going from -> as the last step, LineBuilder aligns the line content (runs) vertically but only when the LineBuilder is not in the preferred-width computation mode. to -> LineBuild only takes care of the run placement horizontally (run size, logical left) and does not do any kind of alignment while LineBox constructs proper inline boxes for the inline content and aligns them both vertically and horizontally as needed.