/** Disable/enable the move-to-newer/older buttons. */ @Override protected void updateNavigationArrows() { final MessageOrderManager orderManager = getMessageOrderManager(); if (orderManager == null) { // shouldn't happen, but just in case mMessageCommandButtons.enableNavigationButtons(false, false, 0, 0); } else { mMessageCommandButtons.enableNavigationButtons( orderManager.canMoveToNewer(), orderManager.canMoveToOlder(), orderManager.getCurrentPosition(), orderManager.getTotalMessageCount()); } }