From the early versions of Plone I was developing custom styles for Plone sites (custom Plone Skins) using general designer's approach. The development was done TTW. I had to go to the portal_skins tool, create custom skin layer, register it with portal skins properties, set the newly created skin in the ZMI. Then customizing needed css files, JavaScripts, page templates, altering some properties, adding images. These activities resulted in new appearance for the Plone site - custom plone skin. The more Plone skins were developed - the more clear was the need in file-system implementation of Plone skins, making them to be software that could be easily deployable and independent from the content. I will try to highlight positives and negatives of TTW skinning compared to file-system-product skinning from designer's point of view.

Why I prefer TTW over file-system-based plone skin development?

Under "skin developer" I mean is skin designer who implements the design into the Plone.

• TTW more usable for skin developer
  Designer do not need to be a developer to work TTW. It is much more simple to do not care about file-system product internal structure. Just customize CSS, templates, properties and see the result after browser refresh.

• Any Plone visualization can be obtained from TTW Plone skin development
  The TTW approach is very convenient and all-sufficient for achieving any visual representation and dynamic behavior of Plone IMHO. I can't see any restrictions.
  

• TTW is the only choice when skin developer has limited access to the file system

What are the disadvantages of TTW approach for Plone skin development?

• Reproducibility, smaller installation time and less deployment efforts
  After Plone skin is developed on a local PC, there is the need to do many single steps to install the skin on the remote server. Sometimes you need to affect some portal settings: general settings, navigation settings, portlet settings, etc... When you  install the skin on the remote server you need to redo all those steps for skin to function correctly.

• How to track skin changes properly?
  Sometimes you do changes in Plone skin, you may do changes quite often, Plone skin is different after every single change. What happens when you need to rollback to some earlier version and go on from that point? This is solved with Version Control System involved in development of file-system plone skin product.

• Performance
  Very important thing is Plone skin performance. While Plone skin is developed by TTW it can't have such performance as file-system plone skin product have.

Plone Skin Dump

Generally speaking TTW approach is more usable for designers, file-system development is preferable for programmers. Both of them have advantages and disadvantages and have a right to exist. Here at Quintagroup we wanted to have advantages of both approaches. Solution would be oriented for a Plone designer's use... And have advantages of file-system product. As the result Plone Skin Dump product was developed.