Most multi-step process UI patterns include something for a "which step am I on" wayfinding, the big question is usually how few steps can you get away with not showing this UI element, 2? 3? 4? its murky. Since we don't have that many complex multi-step processes, this was an idea to sidestep the whole issues. button is blue, "I'm not done," button is green, "I'm done"  I think it will be a subtle distinction for most users, some may not even notice, and thats fine. If in the end we declare it a total failure we can just clone mw.ui.button.constructive over mw.ui.button.progressive and call it a day.  The rules for when you use one over the other are pretty clear in most cases. In general we always look to existing patterns we can borrow or steal, but sometime we invent something new. This is that case, we could use one of the many breadcrumbs, pagination hacks, progress bars, etc. but these feel over-designed for our simple 2-3 step processes, and are more cognitive weight for users that we really want. We could try to use an off the shelf pattern and adjust it for our needs, or we could try something new. let's try something new.  

p.s. Preview would be a progressive action, not a neutral one, since the user would need to Save to finish the process flow of making an edit.