There are many website add ons also known by the names of "overlays", "shims", and "widgets" that promise to make an inaccessible web application or website accessible. None that the university has examined make good on their claims. Several, in fact, were mentioned in lawsuits in 2020 and 2021 as having made a bad experience worse. In most cases the overlay provides functionality already available in the browser and system settings but does so in a disruptive manner, often causing accessibility issues.
Making sure that a website is accessible after the fact is work, but it is time well spent, as not only the end product will be more inclusive, but the people doing the work will learn from the experience and be able to apply this new knowledge in the future.
Key Points
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Overlays duplicate accessibility settings already available in operating systems.
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Users are familiar with these operating system options and they can conflict with overlays.
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Overlays claim to be able to repair form labels. This is done with heuristics and therefore cannot be 100 percent reliable.
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Overlays cannot repair the accessibility of PDF files.
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Overlays can have unpredictable results when JavaScript frameworks change the page as the user interacts with it.
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Overlays can also cause unpredictable results when trying to remediate keyboard navigation issues.
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Meeting the official guidelines requires conformance with all success criteria and overlays are known not to fix all conformance issues.
More Information
- The Overlay Fact Sheet has been signed by many prominent legal and technical leaders in Digital Accessibility
- UsableNet's 2021 year end summary of digital accessibility lawsuits (scroll to the Widgets and Overlays section)
- A New York Times article "For Blind Internet Users, the Fix Can Be Worse Than the Flaws" outlining the negative impact of overlays on real people.