I think Jared and May concluded that quiet buttons start out gray and reveal any constructive/progressive/destructive color on hover and active. This is implemented in patch set 10, installed on http://ee-flow-extra.instance-proxy.wmflabs.org/wiki/Special:UserLogin (plus all the other URLs on that instance).
I also hacked in the darken behavior on MediaWiki (lessphp doesn't implement shade and tint!), and removed the hyperlink underline on mouseover and click.
I think that's it for technical issues. If so we're ready for a FINAL button meeting where we agree on this button set for Login/Create account, PasswordReset, Flow, and the few other extensions using it. No extraneous topics, no new ideas, just sign off on what we have and +2 the two gerrit patches.