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
String storeValue = null;
		IStructuredSelection selection = (IStructuredSelection) getTreeViewer().getSelection();
		if (selection.size() == 1) {
			IPreferenceNode node = (IPreferenceNode) selection.getFirstElement();
			storeValue = node.getId();
		}
		setSelectedNodePreference(storeValue);
	}
	/**
	 * Get the name of the selected item preference
	 */
	protected void setSelectedNodePreference(String pageId) {
		lastPreferenceId = pageId;
	}
	/**
	 * Changes the shell size to the given size, ensuring that
	 * it is no larger than the display bounds.
	 * 
	 * @param width the shell width
	 * @param height the shell height
	 */
	private void setShellSize(int width, int height) {
		getShell().setSize(width, height);
		constrainShellSize();
	}
	/**
	 * Show the new message
	 */
	private void showMessage(String newMessage, Image newImage) {