diff --git a/core/modules/layout/includes/layout.admin.inc b/core/modules/layout/includes/layout.admin.inc
index 8bc2270..489e8a3 100644
--- a/core/modules/layout/includes/layout.admin.inc
+++ b/core/modules/layout/includes/layout.admin.inc
@@ -127,7 +127,7 @@ function layout_master_webservice(Display $display, $a=NULL, $b=NULL, $c=NULL) {
     // stores complete layout
     case 'layout':
       $blockInfo = array();
-      // Shove the
+      // Set payload - this *obviously* needs to be validated.
       foreach ($payload['regions'] as $region) {
         foreach ($region['blockInstances'] as $blockInstance) {
           $block = $blockInstance['id'];
diff --git a/core/modules/layout/js/collections/collections.js b/core/modules/layout/js/collections/collections.js
index b71c783..c41a80a 100644
--- a/core/modules/layout/js/collections/collections.js
+++ b/core/modules/layout/js/collections/collections.js
@@ -19,8 +19,29 @@
 
   Drupal.layout.BlockInstancesCollection = Backbone.Collection.extend({
     model: Drupal.layout.BlockInstanceModel,
+    initialize: function() {
+      // Reorder every time a block instance is added or removed.
+      this.on('add', this.reorder, this);
+      this.on('remove', this.reorder, this);
+    },
+    /**
+     * Sorting callback for the collection.
+     * @param {Drupal.layout.BlockInstanceModel}
+     * @return {Number}
+     */
     comparator: function(model) {
       return model.get('weight');
+    },
+    /**
+     * Make sure that weight attribute of the models correspond to their index.
+     */
+    reorder: function(options) {
+      this.each(function (model, index) {
+        model.set('weight', index);
+      });
+      if (!options || !options.silent) {
+        this.trigger('reorder');
+      }
     }
   });
 
diff --git a/core/modules/layout/js/layout.admin.js b/core/modules/layout/js/layout.admin.js
index 79fe84e..43c1563 100755
--- a/core/modules/layout/js/layout.admin.js
+++ b/core/modules/layout/js/layout.admin.js
@@ -2,14 +2,13 @@
 
 "use strict";
 
+var appView;
+
 /**
  * Attach display editor functionality.
  */
 Drupal.behaviors.displayEditor = {
-
   attach: function (context, settings) {
-    var appModel, appView;
-
     function randomId() {
       var chars = "abcdefghiklmnopqrstuvwxyz";
       var randomString = '';
@@ -52,23 +51,47 @@ Drupal.behaviors.displayEditor = {
           id: region.id,
           label: region.label,
           blockInstances:
-            new Drupal.layout.BlockInstancesCollection().reset(region.blockInstances, {silent: true})
+            new Drupal.layout.BlockInstancesCollection().reset(region.blockInstances)
         }));
       });
       return regions;
     }
 
-    // Populate the appModel
-    Drupal.layout.appModel = new Drupal.layout.AppModel({
-      id: drupalSettings.layout.id,
-      regions: generateRegionCollections(drupalSettings.layout.layoutData)
-    });
-    var appView = new Drupal.layout.AppView({
-      model: Drupal.layout.appModel,
-      el: $('#block-system-main'),
-      locked: drupalSettings.layout.locked
-    });
-    appView.render();
+    // Initial attaching.
+    if (!appView) {
+      Drupal.layout.appModel = new Drupal.layout.AppModel({
+        id: drupalSettings.layout.id,
+        layout: drupalSettings.layout.layoutData.layout,
+        regions: generateRegionCollections(drupalSettings.layout.layoutData)
+      });
+      appView = new Drupal.layout.AppView({
+        model: Drupal.layout.appModel,
+        el: $('#block-system-main'),
+        locked: drupalSettings.layout.locked
+      });
+      // @todo: we need to do this in order to circumvent the merge-behavior of
+      // Drupal.ajax on drupalSettings (which makes sense, just not here).
+      drupalSettings.layout.layoutData = {};
+      appView.render();
+    } else {
+      // Drupal.ajax has (good) reasons to call the attach function three times
+      // per response (triggered by layout select menu). But we
+      // need this only once and we need to make sure that the layout data is
+      // replaced not merged, that's why we do this stunt. There needs to be
+      // some form of making this less awkward.
+      if (drupalSettings.layout.layoutData.id) {
+        // Updating the model will trigger an rendering as appropriate.
+        Drupal.layout.appModel.set({
+          id: drupalSettings.layout.id,
+          layout: drupalSettings.layout.layoutData.layout,
+          regions: generateRegionCollections(drupalSettings.layout.layoutData)
+        });
+        // @todo: we need to do this in order to circumvent the merge-behavior of
+        // Drupal.ajax on drupalSettings (which makes sense, just not here).
+        drupalSettings.layout.layoutData = {};
+      }
+    }
+
   }
 };
 
diff --git a/core/modules/layout/js/models/app-model.js b/core/modules/layout/js/models/app-model.js
index b7535b4..6fd97e7 100644
--- a/core/modules/layout/js/models/app-model.js
+++ b/core/modules/layout/js/models/app-model.js
@@ -15,7 +15,7 @@
     },
     defaults: {
       'id': null,
-      'template': null,
+      'layout': null,
       'regions': null,
       'config': null
     }
diff --git a/core/modules/layout/js/views/app-view.js b/core/modules/layout/js/views/app-view.js
index 4b8985a..b9c2814 100644
--- a/core/modules/layout/js/views/app-view.js
+++ b/core/modules/layout/js/views/app-view.js
@@ -16,7 +16,7 @@
 
   Drupal.layout = Drupal.layout || {};
   Drupal.layout.AppView = Backbone.View.extend({
-    initialize: function(options) {
+    initializeRegions: function() {
       this.regionsView = new Drupal.layout.UpdatingCollectionView({
         el: this.$el.find('.layout-display'),
         collection: this.model.get('regions'),
@@ -24,6 +24,17 @@
         nestedViewTagName:'div'
       });
     },
+    initialize: function(options) {
+      this.initializeRegions();
+      // Listen to changes of the layout-property for a complete repaint.
+      this.model.on('change:layout', function(m) {
+        this.remove();
+        // Reinitialize region - @todo: find a way of doing this w/o
+        // reinitializing the view.
+        this.initializeRegions();
+        this.render();
+      }, this);
+    },
     render: function() {
       // @todo: this should move to layout.admin.js and provide better handling.
       // Do not setup the js app if another user is currently operating on this
@@ -32,20 +43,10 @@
         return false;
       }
       this.regionsView.render();
-      this.$el.sortable({
-        items: '.block',
-        connectWith: '.connected-sortable',
-        cursor: 'move',
-        stop: function(event, ui) {
-          ui.item.trigger('drop', ui.item.index());
-        }
-      });
       return this;
     },
     remove: function() {
-      this.$el.sortable('destroy');
       this.regionsView.remove();
-      this.$el.remove();
     }
   });
 
diff --git a/core/modules/layout/js/views/blockselectormodal-view.js b/core/modules/layout/js/views/blockselectormodal-view.js
index 5e6a3c4..ea2c600 100644
--- a/core/modules/layout/js/views/blockselectormodal-view.js
+++ b/core/modules/layout/js/views/blockselectormodal-view.js
@@ -19,6 +19,8 @@
     selectBlock: function(e, block) {
       // Model is RegionModel
       var instance = block.createBlockInstance();
+      // Append at the end.
+      instance.set('weight', this.model.get('blockInstances').length);
       this.model.get('blockInstances').add(instance);
       // Remove & close dialog.
       this.remove();
@@ -26,6 +28,7 @@
     tagName: 'ul',
     render: function() {
       this.$el.empty();
+      // @todo: refactor this to use nestedViewContainerSelector.
       this._collectionView = new Drupal.layout.UpdatingCollectionView({
         collection:this.collection,
         nestedViewConstructor:Drupal.layout.BlockListItemView,
diff --git a/core/modules/layout/js/views/region-view.js b/core/modules/layout/js/views/region-view.js
index 8a8834a..d5d1995 100644
--- a/core/modules/layout/js/views/region-view.js
+++ b/core/modules/layout/js/views/region-view.js
@@ -56,12 +56,10 @@
         nestedViewContainerSelector: '.blocks .row'
       });
 
-      // @todo: be selective about what change-events trigger requests to the
-      // server.
-      // "Debounce" rapid sequences of change events to avoid unnecessary requests.
-      blockInstances.on('change', _.debounce(function() {
-        this.saveFullLayout();
-      }, 100), this);
+      // @todo: be more selective about what changes trigger requests to the
+      // server. And let that bubble up to the app-view or only persist the
+      // region-specific changes here.
+      blockInstances.on('reorder', this.saveFullLayout, this);
       blockInstances.on('add', this.saveFullLayout, this);
       blockInstances.on('remove', this.saveFullLayout, this);
     },
@@ -69,36 +67,40 @@
     render:function () {
       this.$el.html(Drupal.theme.layoutRegion(this.model.get('id'), this.model.get('label')));
       this._collectionView.render();
+      // Making the whole layout-region-element sortable provides a larger area
+      // to drop block instances on and allows for dropping on empty regions.
+      this.$('.layout-region').sortable({
+        items: '.block',
+        connectWith: '.layout-region',
+        cursor: 'move',
+        stop: function(event, ui) {
+          ui.item.trigger('drop', ui.item.index());
+        }
+      });
       return this;
     },
 
     remove:function () {
+      this.$el.sortable('destroy');
       this.$el.empty();
       this._collectionView.remove();
     },
 
     reorderInstances:function (event, model, position) {
       var collection = this.model.get('blockInstances');
-      // handle cross collection.
+      var originCollection;
+      // Handle cross-collection drag and drop.
       if (!collection.contains(model)) {
-        // let's remove it from the other first before adding it here.
-        model.collection.remove(model);
+        originCollection = model.collection;
+        // Let's remove it from the other first before adding it here.
+        model.collection.remove(model, {silent: true});
+        // This is set to silent to avoid potential race condition.
+        originCollection.reorder({silent: true});
       } else {
-        if (model.get('weight')==position) {
-          return ;
-        }
-        collection.remove(model);
+        // We'll be re-adding immediately, so no need for rapid-fire events.
+        collection.remove(model, {silent: true});
       }
-      collection.each(function (model, index) {
-        var weight = index;
-        if (index >= position) {
-          weight += 1;
-        }
-        model.set('weight', weight);
-      });
-      model.set('weight', position);
       collection.add(model, {at:position});
-      collection.trigger('reorder');
       this.render();
     }
   });
diff --git a/core/modules/layout/js/views/updatingcollection-view.js b/core/modules/layout/js/views/updatingcollection-view.js
index 3568a27..fb42ebf 100644
--- a/core/modules/layout/js/views/updatingcollection-view.js
+++ b/core/modules/layout/js/views/updatingcollection-view.js
@@ -96,9 +96,25 @@
       // up-to-date.
       this.collection.each(function(m) {
         var nv = this._getViewByModel(m);
-        $el.append(nv.render().$el);
+        // Check that a view could be retrieved.
+        if (nv) {
+          $el.append(nv.render().$el);
+        }
       }, this);
       return this;
+    },
+
+    /**
+     * Remove all nested views.
+     * @todo: should we instead remove the models from the collection? Currently
+     * we leave the collection intact but retrieve each nested view and remove it.
+     */
+    remove: function() {
+      // Cleanup.
+      this.collection.each(function(m) {
+        this._removeModel(m);
+      }, this);
+      this._getContainerElement().remove();
     }
   });
 
diff --git a/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php b/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
index cac0407..e40a6c0 100644
--- a/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
+++ b/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
@@ -107,7 +107,7 @@ public function mapBlocksToLayout(LayoutInterface $layout) {
         // No need to do anything.
       }
       // Then, try to remap using region types.
-      else if (!empty($types[$info['region-type']])) {
+      else if (isset($types[$info['region-type']]) && !empty($types[$info['region-type']])) {
         $info['region'] = reset($types[$info['region-type']]);
       }
       // Finally, fall back to dumping everything in the layout's first region.
diff --git a/core/modules/layout/lib/Drupal/layout/DisplayFormController.php b/core/modules/layout/lib/Drupal/layout/DisplayFormController.php
index 3d0cc3f..802cacb 100755
--- a/core/modules/layout/lib/Drupal/layout/DisplayFormController.php
+++ b/core/modules/layout/lib/Drupal/layout/DisplayFormController.php
@@ -38,17 +38,6 @@ public function form(array $form, array &$form_state, EntityInterface $display)
       'layout' => isset($display->layout) ? $display->layout : reset($layout_keys)
     );
 
-    // @todo: we need proper lock & dirty handling.
-    // @todo: this needs to happen in the client to.
-    if (isset($display->dirty) && $display->dirty) {
-      $form['dirty'] = array(
-        '#type' => 'container',
-        '#attributes' => array('class' => array('view-locked', 'messages', 'warning')),
-        '#children' => t('This display has been edited by you and the changes have not been saved yet.'),
-        '#weight' => -10,
-      );
-    }
-
     $locked = isset($display->locked) && is_object($display->locked) && $display->locked->owner != $GLOBALS['user']->uid;
     // Copied from ViewsEditFormController
     if ($locked) {
@@ -80,8 +69,6 @@ public function form(array $form, array &$form_state, EntityInterface $display)
       }
     }
 
-
-
     $form['layout'] = array(
       '#type' => 'select',
       '#title' => t('Template'),
@@ -98,6 +85,16 @@ public function form(array $form, array &$form_state, EntityInterface $display)
     // To support the Ajax interaction, remap the display to the newly selected
     // layout. This will reorganize the blocks as appropriate.
     if (!isset($display->layout) || ($form_state['values']['layout'] != $display->layout)) {
+      // @todo: clean this up - this is highly likely to be the wrong place
+      // to alter the TempStore.
+
+      // But if i *don't* reload the blockInfo property of the  Display, it can
+      // be "stale" and overwrite changes made via the webservice.
+      $reloaded_display = layout_master_cache_load($display->id);
+      // Need to copy selectively (because just setting $display = $reloaded_display
+      // breaks other things).
+      $display->set('blockInfo', $reloaded_display->get('blockInfo'));
+      // Now remap.
       $layout = layout_manager()->createInstance($form_state['values']['layout'], array());
       $display->remapToLayout($layout);
       // Store changes in TempStore.
@@ -141,14 +138,6 @@ private function layoutDemonstration(EntityInterface $display) {
   }
 
   /**
-   * Temporary implementation of block markup generation.
-   */
-  private function layoutBlock($block_id) {
-    $block_id = str_replace('block.', '', $block_id);
-    return '<div id="block-' . $block_id . '" class="block"><div class="block-master"><div class="information"><span class="type-indicator mb-text">M</span><span class="label mb-text">' . $block_id . '&nbsp;block</span></div><div class="operations"><span class="gear mb-gear"></span></div></div></div>';
-  }
-
-  /**
    * Overrides Drupal\Core\Entity\EntityFormController::actions().
    */
   protected function actions(array $form, array &$form_state) {