I am not 100% it would apply to xara flyouts but the following article suggests that initially hidden (not visible) content is indexed but weighted lower than visible content.
https://www.freshegg.co.uk/blog/tech...hidden-content
All common sense really, make sure really important stuff is visible, perhaps a tag cloud type section in the footer would be a compromise if you want a 'safety net'.
I also recommend signing up to Google search console, which is replacement for Google webmaster tools, this allows you to submit sitemaps, helps you analyze many things including keywords etc.