Step by step is NOT the main feature of CB Conditional. It was a complete after-thought in it's development that I thought would be cool to have. The main feature is conditional display of fields based off other fields values, which works flawlessly. GJ at this time is my absolutely priority as 2.4 needs to be released yet have issues still needing to be fixed. Shortly after several incubator projects are going to be receiving updates.

Agree and not agree Actually, i was surprised to find the tabbed registration in CB-Conditional. The visual aspect might be relatively easy, because of jQuery and CSS selectors... but i understand the difficult part of validation and dependencies.

Hard part isn't just the validation as for me PHP is quite easy. jQuery however is a whole other beast fighting for visual control. So much has to be factored in to ensure it works and even then 1 conflict and BAM all that work is undone which unfortunately conflicts are going to happen no matter what I do. CBSubs and CB Conditional in this case are at war for who can control what field and CB Conditional is winning by reasserting the dom causing CBSubs events to no longer work. I've to find a way to MOVE the existing dom instead of simply delete and re-add.

I wonder why tabs/sliders are not a display option for any CB tab? As we all know, there are already display variants available in tab parameters... can you tell me why this technique is not "extendable" or re-usable for Registration? At least it is available on Profile display, and it would be great to have the same on Registration/Edit.

Each field and tab has an output/reason. This determines internally through a series of API how exactly it will display right do the last variable in its HTML. There's no triggers for me to alter this and extend it how I please so the only method was to redesign through jQuery. Much much more is planned for CB 2.0 as a lot of the ideas and projects I develop on incubator move to the core of CB; you can see previous of our conditional engine inside of CBSubs.

Is it possible to extend the "tab-style" popup and the code behind it?
Obviously, the difference between Register/ProfileView/ProfileEdit might be an "old relic" of CB Its about time to improve and consolidate this part... hopefully in CB2.0...

Yup, the tabs are jQuery UI tabs so any jQuery UI theme you apply, will work to restyle the tabs. They've even a cool style generator that can be found below.

jqueryui.com/themeroller/#themeGallery