Bug 65276 [Preferences] Preference dialog should disable OK when okPressed
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/PreferenceDialog.java
}
	/**
	 * 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) {
		Rectangle preferred = getShell().getBounds();
		preferred.width = width;
		preferred.height = height;
		getShell().setBounds(getConstrainedShellBounds(preferred));
	}
	/**
	 * Shows the preference page corresponding to the given preference node.
	 * Does nothing if that page is already current.
	 * 
	 * @param node
	 *            the preference node, or <code>null</code> if none
	 * @return <code>true</code> if the page flip was successful, and
	 *         <code>false</code> is unsuccessful
	 */
	protected boolean showPage(IPreferenceNode node) {
		if (node == null)
			return false;
		
		if (node.getPage() == null)