[css-text] cursive shaping breaks needs better scoping #698
Description
8.3. Shaping Across Element Boundaries
https://drafts.csswg.org/css-text/#boundary-shaping
previous discussion on this topic can be found at:
http://www.w3.org/Mail/flatten/index?subject=Arabic+letters+connecting+between+elements+with+display%3A+inline&list=www-style
Text shaping should not be broken across inline box boundaries otherwise, if it is reasonable and possible for that case given the limitations of the font technology.
I think this is too broad. I created a set of tests for arabic script text at
https://w3c.github.io/i18n-tests/results/css-text-shaping (click on the link in the left column to see the test run)
The results show that no browser tested maintains the joining behaviour where font-weight and font-style and font-size are different. (Red appears because the spec currently implies that those shouldn't break the cursive shaping.) Those should probably be added to the list of styles that break the text shaping. Either that, or it may be simpler to list styling that should not break shaping.
Note also that a border doesn't break the joining behaviour in Firefox and Edge. This perhaps seems like reasonable behaviour for highlighting items, and i wonder whether we should drop that from the list of things that break shaping? I suppose the argument (as for margins and padding) is that this might have been a block element that has been added inline. It seems a pity, however, that such a possibility would rule out the ability to put a border around one character in a cursive sequence using inline markup when wanted.