diff --git a/HISTORY.md b/HISTORY.md
index d884315b..3a7f9098 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -7,6 +7,8 @@
     * added "pie chart" option to PLOT command in the frequency distribution analysis library
     * added getProjectXML() method to the API
     * new noCloud flag that disables cloud access, thanks, Bernat
+* **Notable Changes:**
+    * security: pause generic WHEN hat blocks when loading a project or importing a sprite until the user clicks the green flag or un-pauses the red stop sign, unless opening it with #run:&noRun
 * **Documentation Updates:**
     * API update
 * **Notable Fixes:**
@@ -17,6 +19,9 @@
     * Russian, thanks, Pavel!
     * German
 
+### 2020-10-27
+* gui, objects, store: pause generic WHEN hat blocks when loading a project or importing a sprite until the user clicks the green flag or un-pauses the red stop sign, unless opening it with #run:&noRun 
+
 ### 2020-10-26
 * objects: added test for the existence of generic WHEN hat blocks
 
diff --git a/snap.html b/snap.html
index 744305be..90684ff4 100755
--- a/snap.html
+++ b/snap.html
@@ -10,8 +10,8 @@
         <script src="src/widgets.js?version=2020-10-06"></script>
         <script src="src/blocks.js?version=2020-10-23"></script>
         <script src="src/threads.js?version=2020-10-08"></script>
-        <script src="src/objects.js?version=2020-10-26"></script>
-        <script src="src/gui.js?version=2020-10-23"></script>
+        <script src="src/objects.js?version=2020-10-27"></script>
+        <script src="src/gui.js?version=2020-10-27"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
         <script src="src/lists.js?version=2020-07-01"></script>
         <script src="src/byob.js?version=2020-10-07"></script>
@@ -20,7 +20,7 @@
         <script src="src/video.js?version=2019-06-27"></script>
         <script src="src/maps.js?version=2020-03-25"></script>
         <script src="src/xml.js?version=2020-04-27"></script>
-        <script src="src/store.js?version=2020-10-21"></script>
+        <script src="src/store.js?version=2020-10-27"></script>
         <script src="src/locale.js?version=2020-10-22"></script>
         <script src="src/cloud.js?version=2020-10-21"></script>
         <script src="src/api.js?version=2020-10-20"></script>
diff --git a/src/gui.js b/src/gui.js
index bc6b78b1..ff52a735 100644
--- a/src/gui.js
+++ b/src/gui.js
@@ -78,7 +78,7 @@ Animation, BoxMorph, BlockEditorMorph, BlockDialogMorph, Note, ZERO, BLACK*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.gui = '2020-October-23';
+modules.gui = '2020-October-27';
 
 // Declarations
 
@@ -2316,6 +2316,10 @@ IDE_Morph.prototype.stopFastTracking = function () {
 };
 
 IDE_Morph.prototype.runScripts = function () {
+    if (this.stage.threads.pauseCustomHatBlocks) {
+        this.stage.threads.pauseCustomHatBlocks = false;
+        this.controlBar.stopButton.refresh();
+    }
     this.stage.fireGreenFlagEvent();
 };
 
diff --git a/src/objects.js b/src/objects.js
index bf43efca..1e471a31 100644
--- a/src/objects.js
+++ b/src/objects.js
@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph,  BooleanSlotMorph,
 localize, TableMorph, TableFrameMorph, normalizeCanvas, VectorPaintEditorMorph,
 AlignmentMorph, Process, WorldMap, copyCanvas, useBlurredShadows*/
 
-modules.objects = '2020-October-26';
+modules.objects = '2020-October-27';
 
 var SpriteMorph;
 var StageMorph;
@@ -6438,6 +6438,18 @@ SpriteMorph.prototype.replaceDoubleDefinitionsFor = function (definition) {
     }
 };
 
+// SpriteMorph controlling generic WHEN hats
+
+SpriteMorph.prototype.pauseGenericHatBlocks = function () {
+    var stage = this.parentThatIsA(StageMorph),
+        ide = this.parentThatIsA(IDE_Morph);
+    if (this.hasGenericHatBlocks()) {
+        stage.enableCustomHatBlocks = true;
+        stage.threads.pauseCustomHatBlocks = true;
+        ide.controlBar.stopButton.refresh();
+    }
+};
+
 // SpriteMorph inheritance - general
 
 SpriteMorph.prototype.chooseExemplar = function () {
@@ -8214,6 +8226,18 @@ StageMorph.prototype.editScripts = function () {
     scripts.focus.fixLayout();
 };
 
+// StageMorph controlling generic WHEN hats
+
+StageMorph.prototype.pauseGenericHatBlocks = function () {
+    var ide = this.parentThatIsA(IDE_Morph);
+    if (this.hasGenericHatBlocks() ||
+            ide.sprites.asArray().some(any => any.hasGenericHatBlocks())) {
+        this.enableCustomHatBlocks = true;
+        this.threads.pauseCustomHatBlocks = true;
+        ide.controlBar.stopButton.refresh();
+    }
+};
+
 // StageMorph block templates
 
 StageMorph.prototype.blockTemplates = function (category) {
diff --git a/src/store.js b/src/store.js
index 4f12fe7b..37ce4f7d 100644
--- a/src/store.js
+++ b/src/store.js
@@ -61,7 +61,7 @@ normalizeCanvas, contains*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.store = '2020-October-21';
+modules.store = '2020-October-27';
 
 
 // XML_Serializer ///////////////////////////////////////////////////////
@@ -709,6 +709,7 @@ SnapSerializer.prototype.loadSprites = function (xmlString, ide) {
         sprite.gotoXY(+model.attributes.x || 0, +model.attributes.y || 0);
         this.loadObject(sprite, model);
         sprite.fixLayout();
+        sprite.pauseGenericHatBlocks();
     });
 
     // restore inheritance and nesting associations
@@ -1650,6 +1651,7 @@ SnapSerializer.prototype.openProject = function (project, ide) {
         ide.hasChangedMedia = true;
     }
     project.stage.fixLayout();
+    project.stage.pauseGenericHatBlocks();
     ide.createCorral();
     ide.selectSprite(sprite);
     ide.fixLayout();