We are working on support for


text in Gecko. This will allow web content (and eventually complete web apps, if desired) to use vertical writing, as traditionally used in East Asia.

In addition to the CSS writing-mode property, this will involve support for text-orientation (which determines whether glyphs within vertical text remain "upright" as if in horizontal text, or are rotated 90° to render "sideways"), and for logical versions of many properties that refer to physical directions (such as margin-left, padding-top, border-bottom, min-width, max-height, etc. etc.), so that stylesheets -- in particular, the UA's built-in stylesheets -- can be written in a form that works for both horizontal and vertical content.

The top-level meta bug covering this work is https://bugzilla.mozilla.org/show_bug.cgi?id=145503.

The major standards relevant to this work are:

This will be part of the standard Gecko engine, available to HTML content across all products and platforms. (At this time, we are not planning to support vertical writing modes for XUL.)

Our intention is to implement and release support for vertical text and layout in stages: initially, vertical mode will be supported for simple blocks and inline elements, including styling and editing text as expected. Some of the simpler form controls such as checkboxes, radio buttons, input fields and textareas should also be usable in the first release. However, more complex controls and layout constructs will not be vertical-enabled until later releases. Thus, the initial release should be adequate to support pages that want to display straightforward blocks of text using vertical writing (e.g. a news site, blog, or ebook reader).

There is already some vertical writing mode support in webkit, blink and IE, and tests are being developed (e.g. see http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/). Current implementations are prefixed, and appear to be somewhat incomplete and/or based on earlier drafts of the specs, but there seems to be a good prospect of browsers converging as the specifications become more stable.

A good deal of the layout work to support writing modes has landed over the past year. It is controlled by the boolean pref "layout.css.vertical-text.enabled", which is currently false by default.

We intend to enable this feature by toggling the vertical-text pref to true in https://bugzilla.mozilla.org/show_bug.cgi?id=1099032 once the code is sufficiently stable. This may be in Gecko 38, if the remaining dependencies can be resolved.


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