This is the follow up to Open discussion on Drupal's themeing capabilities and templating engines., and is more technical in nature than the previous article. This article intends to go into depth about the nature of the current system, and what possible improvements could be made in the future.
It will attempt to refer to as much actual code as possible, so much so that I am starting to wonder wether it would not have been faster for me to just write the code and get it done with, however.. I also feel that it is important that contributing designers have a reference point for the nature of these changes, hence this discussion.
I am only indexing the current Drupal 4.4.0 contributed themes, as they are the only ones which would be able to support all the drupal features. Unsupported themes that should be indexed additionally should please be mentioned in the following discussion.