I love the php theme engine.
I love the way it allows a relative novice to change a few things, and it allows those with the need or the curiosity to do just about anything that they want. It is incredibly flexible and is, I think, one of the biggest drawcards for using drupal.
However, the theming concept is not really carried into the admin pages. Each module seems to, to a large extent, build pages that don't pass variables to themes. The HTML structure of the edit node page is hard coded into the module. This makes it necessary to hack the module in order to add things like id's, or to modify the order of the page. For instance, I like my content management interface to place the publish information etc at the bottom of the page. To achieve this I go into the module and move some code around.
My idea is that modules could use exactly the same theming engine as nodes, passing variables to relevant theme functions. The theme functions would be placed inside the module code, but could be overridden in by a template.
This would allow complete configuration freedom for developing the content management interface. We could then create roles with edit access and give them only the options that we wanted, styled the way we want, just like we do with themes. This could really address some of the perceived 'unfriendliness' of Drupal.
Don't get me wrong - I realise that this would take an incredible amount of work. This is not one of those 'Drupal doesn't do this for me - someone fix it now or I want my money back' posts ;) and I dont expect anyone to do it (although I would be willing to contribute in any way that I could). I am just wondering if anyone else feels that adding theming to the admin pages would really enhance drupal.