[EuiTabs] Consider adding a prop to render tabs vertically

[1Copenut]

@julianrosado asked a great question yesterday about vertical tabs:

Random suggestion as it flies through my head (before I forget again)... vertical tabs, to replicate a gallery-ish type view, would be baller. Xata does this neat code snippet selector (left hand column is links, which changes the code block), and I don't have an easy way to do that in EUI. But I would love to. That is all, thanks.

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@MichaelMarcialis offered a suggestion that we've used EuiFacet in the past to act as vertical tabs:

FWIW, I believe we've used EuiFacetButtons in the past to function akin to vertical tabs. The integrations page being one such example:

https://elastic.github.io/eui/?first=&range=50#/navigation/facet

[1Copenut]

I'd like to offer a counter that we should discuss this in terms of adding a prop to the EuiTabs to realign them as vertical tabs. I've seen the current implementation and have accessibility concerns. The example uses tabs for Browse Integrations and Installed Integrations which is what we expect. The vertical list does not have a semantic relationship with the cards displayed on the right. I feel that our accepted solution needs to make that implicit visual relationship semantic and explicit.

[julianrosado]

Out of curiosity: what I was asking for is basically a tab (each link shows different content in a similar context) but on the integrations page those are filters/facets (each link shows a part of the greater whole). In that context is that still considered non-semantic?

[ryankeairns]

As there are ways to approximate this layout with existing components (as shown above), and the current use cases seem few in number, this won't be prioritized by the EUI team at this time. For now, we'll close this discussion, but please do continue +1'ing / adding new use cases as they will assist the team in setting priority.

In any case, the accessibility needs remain and should be accounted for in any solution.

As always, if a downstream person/team would like to see this in EUI sooner, they are welcome to contribute a PR.