[Usability] cross-desktop coordination?

[Jacob Beauregard <jake13jake comcast net>]

This has always bothered me. GNOME and KDE have different HIGs, 
different services, different themes, etc. Wouldn't a user have an 
easier time using Linux if libraries shared things?

A user would need to go into KDE's config and set it's theme to be 
similar to GNOME's if they wanted consistency in that aspect. Why not 
share?

Users can't choose whether they're using a default GNOME save-file 
dialog or a default KDE save-file dialog for saving a file. Why not let 
the user choose and let the libraries share that choice?

Why can't a Common HIG be created?