Add in a notification for unsaved changes.

assets/js/admin/settings-views-html-settings-tax.js

@@ -16,6 +16,7 @@
 			paginationTemplate = wp.template( 'wc-tax-table-pagination' ),
 			$table             = $( '.wc_tax_rates' ),
 			$tbody             = $( '#rates' ),
+			$p_unsaved_msg     = $( '#unsaved-changes' ),
 			$pagination        = $( '#rates-pagination' ),
 			WCTaxTableModelConstructor = Backbone.Model.extend({
 				setRateAttribute : function( rateID, attribute, value ) {
@@ -85,9 +86,11 @@
 				},
 				setUnloadConfirmation : function() {
 					this.needsUnloadConfirm = true;
+					$p_unsaved_msg.show();
 				},
 				clearUnloadConfirmation : function() {
 					this.needsUnloadConfirm = false;
+					$p_unsaved_msg.hide();
 				},
 				unloadConfirmation : function(event) {
 					if ( event.data.view.needsUnloadConfirm ) {

includes/admin/settings/views/html-settings-tax.php

@@ -45,6 +45,8 @@ if ( ! defined( 'ABSPATH' ) ) {
 	</tbody>
 </table>
 
+<p id="unsaved-changes" style="display:none;"><?php _e( 'There are unsaved changes.', 'woocommerce' ); ?></p>
+
 <script type="text/html" id="tmpl-wc-tax-table-row">
 	<tr class="tips" data-tip="<?php echo esc_attr( sprintf( __( 'Tax rate ID: %s', 'woocommerce' ), '{{ data.tax_rate_id }}' ) ); ?>" data-id="{{ data.tax_rate_id }}">
 		<td class="sort">