En Web Accessibility Overlays Do Not Work se explican algunos de los problemas que tienen este tipo de soluciones.
En Not All Accessibility Overlays Are Created Equal se clasifica este tipo de software en dos tipos:
There are two types of overlays: targeted “Custom JavaScript overlays” – customized to the specific page and website, these overlays can make comprehensive changes to any accessibility concern on a specific page, and “Tool-based overlays” often seen in the form of a toolbar, plugin or extension – these make limited, generic changes to the page, some of which can be controlled by the site visitor.Y explica los siguientes problemas que tienen las "tool-based overlay solutions":
- They require people with disabilities to download and use a different tool they aren’t used to, instead of the assistive technology they are comfortable with.
- They require the user to know about and install a custom plugin that might introduce its own accessibility problems.
- They don’t work for native mobile applications, so your website is still at risk for an accessibility-related complaint or lawsuit.
- They only address a limited scope of accessibility issues:
- They provide simple modifications to the page overall, they may change the color contrast, add a focus indicator or add a high contrast mode which addresses only a small number of the possible accessibility barriers.
- They cannot add missing complex keyboard or device interactions, they cannot fix specific site semantics and they cannot add meaning or text alternatives where these are missing.
