`DialogV2` should have `aria-modal="true"`

[iansan5653]

Description

The DialogV2 component enables a focus trap and background overlay by default. This makes it a modal dialog by definition:

A section of content is "modal" means navigation is limited to the area itself and the background (the ancestors and siblings of the modal) is hidden. Setting aria-modal="true" on dialog and alertdialog role containers indicates the presence of a "modal" element to users of assistive technology

By default, items with role="dialog" have aria-modal="false", indicating to screen readers that navigation outside the dialog is possible. But it is not, so this is misleading and can get screen readers into a state where interaction appears possible but is not.

Explicitly setting the aria-modal="true" prop on the Dialog component does not work as a workaround because that prop is not forwarded to the underlying element.

Steps to reproduce

Render a Dialog component from @primer/react/drafts

Version

v35.17.0

Browser

Chrome

[langermank]

Wondering if we might want to close this issue in favor of https://github.com/github/primer/issues/1551 which will include using the PVC Dialog as a reference for markup and accessibility features.

[lesliecdubs]

Thanks for filing @iansan5653, and thanks for the link @langermank!

The PVC Dialog component has been approved by the accessibility team and we have plans to replicate the improved markup in React as part of https://github.com/github/primer/issues/1551. Feel free to follow progress along on that issue, or reach out if you're interested in contributing these changes.

[iansan5653]

Would a PR be accepted for a quick fix to resolve this for now? This is a pretty significant accessibility problem for which there is no good workaround - it seems to me like it would probably be worth shipping the one-line fix for now even if this component would be replaced by that related work eventually.

[lesliecdubs]

@iansan5653 yes, we would be happy to review a PR contribution assuming it's a quick fix! Let me know if you want me to reopen this for you to track against.