Bug 38729 [Preferences] NPE PreferencePage isValid
getContainer may return null
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferencePage.java
*/
	private Point size = null;
	/**
	 * Creates a new preference page with an empty title and no image.
	 */
	protected PreferencePage() {
		this(""); 
	}
	/**
	 * Creates a new preference page with the given title and no image.
	 *
	 * @param title the title of this preference page
	 */
	protected PreferencePage(String title) {
		super(title);
	}
	/**
	 * Creates a new abstract preference page with the given title and image.
	 *
	 * @param title the title of this preference page
	 * @param image the image for this preference page,
	 *  or <code>null</code> if none
	 */
	protected PreferencePage(String title, ImageDescriptor image) {
		super(title, image);
	}
	/**
	 * Computes the size for this page's UI control.
	 * <p>
	 * The default implementation of this <code>IPreferencePage</code>