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
* Create a new <code>TreeViewer</code>.
	 * @param parent the parent <code>Composite</code>.
	 * @return the <code>TreeViewer</code>.
	 * @since 3.0
	 */
	protected TreeViewer createTreeViewer(Composite parent) {
		final TreeViewer viewer = new TreeViewer(parent, SWT.BORDER);
		viewer.addPostSelectionChangedListener(new ISelectionChangedListener() {
			private void handleError() {
				try {
					 
					 
					
					viewer.removePostSelectionChangedListener(this);
					showPageFlippingAbortDialog();
					selectCurrentPageAgain();
					clearSelectedNode();
				} finally {
					viewer.addPostSelectionChangedListener(this);
				}
			}
			public void selectionChanged(SelectionChangedEvent event) {
				Object selection = getSingleSelection(event.getSelection());
				if (selection instanceof IPreferenceNode) {
					if (!isCurrentPageValid()) {
						handleError();
					} else if (!showPage((IPreferenceNode) selection)) {
						
						handleError();
					} else {