Bug 76969 Preference change not propegated.
build N20041024 - open the workbench - popup a menu over the perspective switcher and choose Dock On > Left NOTE that the UI does not respond right away (and it should). Seems that the listener is not being notified of the change.
bundles/org.eclipse.ui/src/org/eclipse/ui/internal/UIPreferenceInitializer.java
true);
		IEclipsePreferences rootNode = (IEclipsePreferences) Platform
				.getPreferencesService().getRootNode()
				.node(InstanceScope.SCOPE);
		final String uiName = UIPlugin.getDefault().getBundle()
				.getSymbolicName();
		rootNode
				.addNodeChangeListener(new IEclipsePreferences.INodeChangeListener() {
					/*
					 * (non-Javadoc)
					 * 
					 * @see org.eclipse.core.runtime.preferences.IEclipsePreferences.INodeChangeListener#added(org.eclipse.core.runtime.preferences.IEclipsePreferences.NodeChangeEvent)
					 */
					public void added(NodeChangeEvent event) {
						if (!event.getChild().name().equals(uiName))
							return;
						((IEclipsePreferences) event.getChild())
								.addPreferenceChangeListener(PlatformUIPreferenceListener.getSingleton());
					}
					/*
					 * (non-Javadoc)
					 * 
					 * @see org.eclipse.core.runtime.preferences.IEclipsePreferences.INodeChangeListener#removed(org.eclipse.core.runtime.preferences.IEclipsePreferences.NodeChangeEvent)
					 */
					public void removed(NodeChangeEvent event) {
						
					}
				});
	}
}