What to do about the `rowgroup` discrepancy between the spec and implementations?

[cookiecrook]

The first HTML-AAM results landed today in WPT. In particular, the table roles tests show that Chrome and WebKit treat thead/tbody/tfoot as ignored (literals none and "" respectively) rather than rowgroup from the HTML-AAM spec.

https://wpt.fyi/results/html-aam/table-roles.html?label=master&label=experimental&aligned

Do we need to resolve this to use rowgroup or should this be a case where the spec should reflect the current reality rather than requiring an arbitrary change without substantial user benefit?

[stevefaulkner]

@cookiecrook what counts as substantial user benefit? and why consider it arbitrary when they are defined in HTML as:

represents the block of rows

[cookiecrook]

I just mean that that browser and platform accessibility implementations haven't used them… Ever, as far as I can tell. I've verified this in Gecko, Chromium, and WebKit. They aren't reflected in any accessibility inspector, either.

As far as I know, there is no special accessibility behavior for thead/tbody/tfoot. I am aware there is is special behavior when printing large tables that span multiple pages of paper (the thead and tfoot are repeated on each page) but as far as AAMs and AT are concerned, these are ignored elements, and always have been.

why consider it arbitrary?

This is in the context of WPT tests for HTML-AAM. Passing these values would require a change in every browser that introduces risk without any user benefit that I can perceive, and possible cascade changes to a variety of assistive technologies.

what counts as substantial user benefit?

In this case any user benefit would be worth discussing. I don't see any.

Since the implementations are aligned and there isn't a user-driven clamor to support the rowgroup role as a new feature, I'd suggest that:

• the mappings for thead/tbody/tfoot be changed to ignored/none in the HTML-AAM spec.
• the rowgroup role be considered for deprecation in ARIA.

…unless there is some functionality specific to Windows that I'm missing in my Mac-side investigations of these browser implementations.

[cookiecrook]

These are thead elements (same for tbody and tfoot) in:

Chromium:

WebKit:

I can't find any representation of this in Gecko's dev tools. There's also no similar concept I'm aware of in the Xcode Accessibility Inspector for macOS or iOS. If you find something similar on Windows, please share.

[jcsteh]

Gecko normally chooses not to expose thead, tbody and tfoot because they don't really serve much of a purpose, especially given that tables always have a tbody. However, if you force an Accessible to be created (e.g. tabindex or aria-label), Gecko will create an Accessible and it will have the rowgroup role.

[stevefaulkner]

@jcsteh that makes sense, @cookiecrook @aleventhal does this sound reasonable?

default thead, tbody and tfoot have a generic role
if tabindex or accname present they are exposed as rowgroup?

[jcsteh]

To be clear, Gecko doesn't expose them with a generic role if there's no tabindex, aria-label, etc. They don't exist in the a11y tree at all, more like role="none". As I understand it, those two things are different, albeit subtly so.

[jcsteh]

Having said that, I think there's some general confusion around generic things that needs to be sorted out. For example, div and span map to role generic, but both Chromium and Gecko don't always expose them in the a11y tree to improve performance/minimise tree complexity.

Edit: Chrome always exposes generics in the internal a11y tree, but marks them as ignored, so they're effectively not exposed to platform APIs. Firefox doesn't have a concept of ignored; it just doesn't include them in the tree at all in some cases.

[stevefaulkner]

@jcsteh wrote:

Gecko doesn't expose them with a generic role if there's no tabindex, aria-label, etc. They don't exist in the a11y tree at all, more like role="none".

no role works for me

[MarioBatusic]

Is there any real use for the rowgroup role for the assistive technologies? I found it ever only a required grouping structure without any usefulness for AT.

[jnurthen]

The only usefulness I have found is to allow you specify a grouping as uninteresting when the browser would otherwise try to expose it as a generic breaking the table structure.
This is particularly true for FF where something gets exposed in the a11y tree for scrollable tables - setting this node to rowgroup is the only hack I can find to make these situations work without breaking the table structure. (the default exposed generic plays havoc with the a11y tree)

[cookiecrook]

@stevefaulkner wrote:

@jcsteh that makes sense, @cookiecrook @aleventhal does this sound reasonable?

I'll update the test and find out what Chromium and WebKit do with those.

@jnurthen wrote:

The only usefulness I have found is to allow you specify a grouping as uninteresting when the browser would otherwise try to expose it as a generic breaking the table structure.

I think the same would be true whether you used role=none or role=rowgroup [Update: fixed typo role=tbody]

[cookiecrook]

I get different results on Chrome running locally ("rowgroup" w/ or w/o the tabindex) than in Chrome on the WPT CI servers ("none" w/o tabindex, and "rowgroup" w/tabindex). @aleventhal any chance that's a recent change in Chromium?

WebKit returns no role ("") in both circumstances on current STP.