...This new design is quite ready, and we planned to deploy it on our common.css a few weeks ago in order to run some tests with new users. But some users has some rationale concerns about the deployment itself: we planed to create a new design by adding new CSS to the common.css file.
This involves an important risk of conflict if there is an important skin update in the future.
For us, next steps are:
1/ validate the choices we made for this new interface,2/ create a separate skin (with an extension? An other solution?).
* in order to deploy this new design, we can create an extension.
We have volunteers for this, with strong skills (some of them are already volunteers developers for MediaWiki). But is it the best way? Is there other ideas or solutions?