diff --git a/core/modules/block/js/block.js b/core/modules/block/js/block.js
index edc953b..83ae1b7 100644
--- a/core/modules/block/js/block.js
+++ b/core/modules/block/js/block.js
@@ -63,12 +63,13 @@
         return;
       }
 
-      var table = $('#blocks');
+      var $table = $('#blocks');
       // Get the blocks tableDrag object.
       var tableDrag = Drupal.tableDrag.blocks;
       // Add a handler for when a row is swapped, update empty regions.
       tableDrag.row.prototype.onSwap = function (swappedRow) {
-        checkEmptyRegions(table, this);
+        checkEmptyRegions($table, this);
+        updateLastPlaced($table, this);
       };
 
       // Add a handler so when a row is dropped, update fields dropped into new regions.
@@ -98,7 +99,7 @@
           regionField.val(regionName);
         }
 
-        updateBlockWeights(table, regionName);
+        updateBlockWeights($table, regionName);
       };
 
       // Add the behavior to each region select list.
@@ -109,15 +110,33 @@
           var select = $(this);
 
           // Find the correct region and insert the row as the last in the region.
-          table.find('.region-' + select[0].value + '-message').nextUntil('.region-message').eq(-1).before(row);
+          $table.find('.region-' + select[0].value + '-message').nextUntil('.region-message').eq(-1).before(row);
 
-          updateBlockWeights(table, select[0].value);
+          updateBlockWeights($table, select[0].value);
           // Modify empty regions with added or removed fields.
-          checkEmptyRegions(table, row);
+          checkEmptyRegions($table, row);
+          // Update last placed block indication.
+          updateLastPlaced($table, row);
+          // Show unsaved changes warning.
+          if (!tableDrag.changed) {
+            $(Drupal.theme('tableDragChangedWarning')).insertBefore(tableDrag.table).hide().fadeIn('slow');
+            tableDrag.changed = true;
+          }
           // Remove focus from selectbox.
           select.trigger('blur');
         });
 
+      var updateLastPlaced = function ($table, rowObject) {
+        // Remove the color-success class from new block if applicable.
+        $table.find('.color-success').removeClass('color-success');
+
+        var $rowObject = $(rowObject);
+        if (!$rowObject.is('.drag-previous')) {
+          $table.find('.drag-previous').removeClass('drag-previous');
+          $rowObject.addClass('drag-previous');
+        }
+      };
+
       /**
        * Update block weights in the given region.
        *
@@ -140,8 +159,8 @@
           });
       };
 
-      var checkEmptyRegions = function (table, rowObject) {
-        table.find('tr.region-message').each(function () {
+      var checkEmptyRegions = function ($table, rowObject) {
+        $table.find('tr.region-message').each(function () {
           var $this = $(this);
           // If the dragged row is in this region, but above the message row, swap it down one space.
           if ($this.prev('tr').get(0) === rowObject.element) {
diff --git a/core/modules/block/src/BlockListBuilder.php b/core/modules/block/src/BlockListBuilder.php
index 43d7a1c..219ff27 100644
--- a/core/modules/block/src/BlockListBuilder.php
+++ b/core/modules/block/src/BlockListBuilder.php
@@ -257,7 +257,7 @@ protected function buildBlocksForm() {
             ),
           );
           if ($placement && $placement == Html::getClass($entity_id)) {
-            $form[$entity_id]['#attributes']['class'][] = 'color-warning';
+            $form[$entity_id]['#attributes']['class'][] = 'color-success';
             $form[$entity_id]['#attributes']['class'][] = 'js-block-placed';
           }
           $form[$entity_id]['info'] = array(