the Opening Scholarly Communication in the Social Sciences (OSCOSS) project and Fidus Writer have just released version 3.2.0 of the main text editor with an OJS connector. This is the first release of the connector, and although we have tested it a fair bit, we are always interested in feedback on how to do it even better. Thanls also to @asmecher for his help here in the forum (and on site during his visit last year).
You can find the release announcement with videos here: https://www.fiduswriter.org/2017/06/20/fidus-writer-3-2-release-with-plugins/
The plugin has been enabled on the Fidus Writer instance running at GESIS: https://fiduswriter.gesis.org but the way it's done, an administrator needs to connect a particular journal with a Fidus Writer instance, so you won't be able to do much beyond submit an article to one of our three test journals.
You can find the plugin code on the OJS side here: https://github.com/fiduswriter/ojs-fiduswriter (GPL v2) and the plugin on the Fidus Writer side here: https://github.com/fiduswriter/fiduswriter-ojs (AGPL).