XWiki: Improving web accessibility with respect to backward compatibility

XWiki is an open source software that has celebrated its twentieth birthday last year. This knowledge management web platform gives a lot of tools for users to customize it to their own needs. Because of this wide ecosystem, one of the most important properties of our software is backward compatibility. In the recent years, the need for our project to be up to standards concerning accessibility has arisen. I was in charge of improving the accessibility of XWiki standard. I'll show you the roadblocks we found as a community and the workarounds we used to improve accessibility without breaking (too much) backward compatibility.