This is intended to be the bug where we'll toggle the layout.css.vertical-text.enabled pref to true, so that vertical writing mode can actually be used. This will not be the end of work on vertical writing mode, as the initial release will not support vertical mode for all elements or CSS constructs; e.g. tables, grid, form controls, etc., etc., may be horizontal-only at first. Add "depends on" references here for the vertical writing-mode bugs that are essential to fix before we can usefully enable the feature. Additional aspects of vertical support that we want to implement eventually, but that need not block the initial release, should be marked as blocking (directly or indirectly) the main writing-mode bug instead of this one.

Here's the patch to enable writing-mode; we're not ready to consider landing this yet, though.

Note that the patch in bug 1082017 will need to land together with this bug, otherwise we'll get mochitest failures. (But it can't land earlier, because it depends on writing-mode being supported.)

(In reply to Jonathan Kew (:jfkthame) from comment #2) > Note that the patch in bug 1082017 will need to land together with this bug, > otherwise we'll get mochitest failures. (But it can't land earlier, because > it depends on writing-mode being supported.) This is no longer an issue, as that patch was modified so as to land safely, independently of the pref change here.

Time to consider flipping the pref on non-release channels (nightly/dev), so that we can begin to get wider testing of what's been implemented so far? This will also mean that the writing-mode tests start running on mozilla-central, which IMO is highly desirable.

If we do bug 1134598 separately, then all that's left here is the pref change.

As per discussion with jet/dbaron/heycam today, the proposal is to do this *after* next week's uplift.

... #ifndef RELEASE_BUILD, that is. With notification to firefox-dev and dev-gaia that it's enabled for nightly/aurora only, so they shouldn't depend on it yet.

Tracking for Firefox 39.

Release Note Request (optional, but appreciated) [Why is this notable]: Cool new feature on dev channels. [Suggested wording]: Vertical text mode enabled by default on Developer Edition [Links (documentation, blog post, etc)]: https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode

Jonathan, is this likely to stay enabled or be turned off when 39 moves to beta? Would exploratory testing help or does this need the automated tests for us to feel that it's ready for release? Thanks.

For 39, and probably another cycle or two, it'll stay disabled on beta/release channels. (The pref is subject to #ifdef RELEASE_BUILD in all.js.) Bug 1138384 will track enabling the feature on release. (It's not primarily a question of testing, but of feature completeness: there are some substantial parts of CSS layout that do not yet handle vertical mode, such as tables.)

Updated: https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode and https://developer.mozilla.org/en-US/Firefox/Releases/39#CSS