/// <summary>
        /// Checks the states of the map and network view buttons based on the selected river network node.
        /// </summary>
        private void checkViewButtonState()
        {
            StateMod_RiverNetworkNode rin = getSelectedRiverNetworkNode();

            if (rin.getGeoRecord() == null)
            {
                // No spatial data are available
                __showOnMap_JButton.setEnabled(false);
            }
            else
            {
                // Enable the button...
                __showOnMap_JButton.setEnabled(true);
            }
        }