Focus-visible styles on iframe when tabbing

[JayPanoz]

We don’t currently have any :focus-visible styling when the iframe is tabbed, unlike every other interactive element of the UI. So unless there’s a link in the resource displayed in the iframe for instance, there is no visual indication that you’ve just tabbed into the contents.

However, this is trickier that it may seem at first sight, given the iframe is the document.activeElement, but doesn’t receive :focus nor :focus-visible – unless I’m missing something, it’s the content within that does.

[HadrienGardeur]

I've noticed that on Thorium, we can lose the current position when tabbing back into the content (I'm redirected to the beginning of the chapter). Is this something you ever looked into @danielweck?

[danielweck]

See #49 (comment)
Thank you :)

[danielweck]

@HadrienGardeur to be clear: keyboard-tabbing into an EPUB HTML document only "works" (only useful) if the DOM contains tabbable/focussable elements, such as hyperlinks or buttons (otherwise, the focus moves to whatever follows the iframe, skipping the content entirely). The user story is completely different for screen reader users, who benefit from fine-grain linear and hierarchical navigation (tab navigation is very coarse, by comparison).