Ask HN: What are your biggest Web Accessibility Complaints?

Hey HNers,

I'm in the process of building a web project and want to make sure anyone with disabilities can use it as best as possible. The project has a lot of javascript and is very interactive i.e. a true webapp.

Anyways I'd like to know what your biggest complaints and gripes are with web applications in terms of accessibility. What do a lot of apps miss or fail to get right? What's annoying?

Thanks in advance!