PaneKit is a framework which provides various features to build 
flexible pane window in any GNUstep or Cocoa applications. 
PKPanesController controls the main user interface
and several presentations are available.
Panes can be build in bundle of Nib or programmingly.
They are registered in PKPaneRegistry and displayed by PKPanesController.

PKPreferencesController and PKPreferencesPaneRegistry
are designed to handle preferences.
It includes an NSPreferencePane implementation (following Cocoa API).

It is based on GSSystemPreferences code written by Uli Kusterer.

WWW: http://www.etoile-project.org/