Hello,
I would suggest the ability to offer an Office document (DOCX, PPTX, XLSX, ODT, ODS, ODP, etc.) preview in Firefox, like Safari on iOS does. It opens them like a link, and you can look the content up. Even if it's ugly, it's quite useful to avoid useless rubbish in the download folder or to open each time an app, which is very slow when an information is searched through a lot of them.
Thank you!