[joe_the_user]

What I consider ideal is a multi-layered structure where a "graphic shell" (Gnome-shell or Unity) sits on top of "agnostic" windows manager code.

The current version of Gnome actually seems "good enough" to do this. My main concern is that it stay that way. To consider an opposite pole, KDE is certainly open source too. But, for example, to use the KDE code to parse the gnome/kde panels start menu you need to import the entire KDE virtual file system. IE, KDE has a monolithic structure in that regard. Uh, it's open and you could rip out this piece of the code but it would be a mess. Gnome isn't that bad... yet.

[xlpz]

There's a tension between making software fast, reliable and attractive and making it completely configurable. The current culture in GNOME, as far as I understand it, is that the primary goal is to provide a great experience for your users, even if extreme configurability needs to suffer in some cases. Others can disagree and try to do different things, but if you want GNOME to agree with you the only route you have is to join the project and change things from within.

[joe_the_user]

As I hope the post you replied to shows, I'm looking for configurability at the programmatic level, not at the end, end user level. Are you saying that is going to suffer too?

Considering Canonical is currently committed to bolting Unity on top of some version of Gnome, that version is going to have to be configurable enough for such purposes. Hopefully that will be the main line of Gnome.