Bug 48364 PreferenceDialog can reopen empty
20031209 When you close the Preferences dialog with an entry other than the default selected you will get an empty entry in the dialog when you reopen STEPS 1) Open the preferences dialog 2) Select the Appearances page 3) Close the dialog 4) Reopen - Workbench will be selected and the contents will be empty
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
final IPreferenceNode node = (IPreferenceNode) nodes.next();
			if (node.getPage() != null) {
				Platform.run(new SafeRunnable() {
					public void run() {
						if (!node.getPage().performCancel())
							return;
					}
				});
			}
		}
		setReturnCode(CANCEL);
		close();
	}
	/**
	 * Clear the last selected node. This is so that we not chache
	 * the last selection in case of an error.
	 */
	void clearSelectedNode() {
		setSelectedNodePreference(null);
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.window.Window#close()
	 */
	public boolean close() {
		List nodes = preferenceManager.getElements(PreferenceManager.PRE_ORDER);
		for (int i = 0; i < nodes.size(); i++) {
			IPreferenceNode node = (IPreferenceNode) nodes.get(i);
			node.disposeResources();
		}
		return super.close();