In vertical writing mode, we appear to do line-breaking OK within a simple block, but if there are embedded spans (<b> or <i> elements, etc) within the line, we get totally inappropriate breaks; it looks like the wrong available width must be getting passed to the child elements for line-breaking purposes. Testcase attached; set the writing mode to vertical-lr and use the slider to vary the size of the <div> within which the text is being displayed. (In vertical-rl mode, the same line-breaking issues occur, but the display is further confused due to bug 1082844 displaying fragments in the wrong places.)

This one turned out to be a trivial oversight from bug 789096. :)

Comment on attachment 8505410 [details] [diff] [review] Fix misuse of physical instead of logical dimension for line breaking. Review of attachment 8505410 [details] [diff] [review]: ----------------------------------------------------------------- Yes, thank you for catching that.