Update "iframe with interactive elements is not excluded from tab-order" rule to manage inert iframe elements

[giacomo-petri]

This pull request manages inert iframe elements in iframe with interactive elements is not excluded from tab-order rule, excluding them from the applicability of the rule.

Updates:

• edited applicability excluding inert iframe elements;
• added definition of inert in applicability;
• added definition of modal (modal dialog);
• added 2 inapplicable examples:
  • iframe with inert attribute
  • modal which overlaps the iframe, making the iframe inoperable

Closes issue(s): https://github.com/act-rules/act-rules.github.io/issues/1965

Need for Call for Review: This will require a 2 weeks Call for Review

---

Pull Request Etiquette

When creating PR:

• [ ] Make sure you're requesting to pull a branch (right side) to the develop branch (left side).
• [ ] Make sure you do not remove the "How to Review and Approve" section in your pull request description

After creating PR:

• [ ] Add yourself (and co-authors) as "Assignees" for PR.
• [ ] Add label to indicate if it's a Rule, Definition or Chore.
• [ ] Link the PR to any issue it solves. This will be done automatically by referencing the issue at the top of this comment in the indicated place.
• [ ] Optionally request feedback from anyone in particular by assigning them as "Reviewers".

When merging a PR:

• [ ] Close any issue that the PR resolves. This will happen automatically upon merging if the PR was correctly linked to the issue, e.g. by referencing the issue at the top of this comment.

How to Review And Approve

• Go to the “Files changed” tab
• Here you will have the option to leave comments on different lines.
• Once the review is completed, find the “Review changes” button in the top right, select “Approve” (if you are really confident in the rule) or "Request changes" and click “Submit review”.
• Make sure to also review the proposed Call for Review period. In case of disagreement, the longer period wins.

[giacomo-petri]

Updates:

• added "inert" definition to be re-used;
• updated the definition of inert by using the "blocked by a modal" html definition;
• removed the modal definition completely (no longer needed);
• added example (inapplicable 6) of showModal() method.

I've kept the inapplicable example n. 7 with the custom modal. Let me know if it's better to remove it completely.

[giacomo-petri]

The name of the referenced rule Iframe with interactive elements is not excluded from tab-order is fine -- as is the content of the rule.

But the name of this PR seems to be a double negative? It is very confusing! And maybe it does not matter?

Please change the PR name. If it were just "update iframe not focusable" I would have twice about the rule!

Title edited. The initial intent was to provide information about the specific update, avoiding a generic label such as "Update iframe rule", which doesn't help in filtering PR. Please, let me know if the new title makes sense.

[Jym77]

Title edited. The initial intent was to provide information about the specific update, avoiding a generic label such as "Update iframe rule", which doesn't help in filtering PR. Please, let me know if the new title makes sense.

As a rule of thumb, I feel it is good to include the full name of the updated rule in the PR title. Including the rule ID can also help tracking them across change of name (the id is the stable name). I usually like to frontload these, but we have no strict PR naming convention.

"rule name" [rule ID]: verb something something. e.g. "iframe with interactive elements is not excluded from tab-order" [akn7bn]: Manage inert iframe element

(I feel that "update rule" is a bit redundant in a PR title, since PR are mostly made to update rules) (the current title is fine, no need to change it again)

[giacomo-petri]

• Accepted all the @Jym77's suggestions about adding the tabindex="-1" attribute to the iframe element;
• Updated the Failed example n. 6 with dialog opened onload instead of after user activation;
• Removed failed example n.7 with "custom modal" as not aligned with the rule;
• Updated references in "inert" definition.

[carlosapaduarte]

Call for review ends June 21

[Jym77]

I don't think my own knowledge is too below average, so I recommend adding links for background reading. Here are two I found useful:

• Introducing inert
• MDN reference inert

@bruce-usab Since ACT rules are intended to be published as official W3C documentation, we tend to avoid direct links (or citation) of commercial third parties, especially when they are themselves major players (we do not want to look like we favour one above the others). As much as we can, we'd rather stick with W3C documentation (HTML living standard, …)

[giacomo-petri]

This PR is in call for review for 2 weeks. Review ends Sept 29th.