webPage.add(new AbstractAjaxTimerBehavior(duration) {
		private static final long serialVersionUID = 1L;

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final CharSequence getCallbackUrl(final boolean onlyTargetActivePage) {
			return String.valueOf(super.getCallbackUrl(onlyTargetActivePage)) + "&pos=" + "window.pos";
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		protected final void onTimer(final AjaxRequestTarget target) {
			final String pos = getRequest().getParameter("pos");
			// process pos ...
		}
	});