diff --git a/HISTORY.md b/HISTORY.md
index 89a47ae0..353104fa 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -7,6 +7,7 @@
     * single blocks palette option, thanks, Michael!
     * web-serial support, thanks, Dariusz Dorożalski!
     * hide any block, including variables and custom helper blocks in palette, also use "hide/show var" primitive on custom blocks (same as on primitives)
+    * generate Parsons Problems from projects: Hide all unused blocks from the scripting area in the palette
     * user defined custom block palettes
     * PWA, thanks, Joan and John, for pioneering this at Robolot and in Mircoblocks!
     * new "blocksZoom=n" url parameter, thanks, Bernat!
@@ -43,6 +44,7 @@
 * scenes, store: store single palette setting per project (for making extensions)
 * gui, scenes, objects: added scene-setting to hide/show category names in the unified palette
 * store: made "hide/show categories in unified palette" setting persistent
+* byob: hide unused blocks in palette
 
 ### 2021-10-11
 * objects: sort order of blocks in custom categories alphabetically in the unified palette
diff --git a/snap.html b/snap.html
index 86a36373..94e96ed1 100755
--- a/snap.html
+++ b/snap.html
@@ -23,7 +23,7 @@
         <script src="src/gui.js?version=2021-10-12"></script>
         <script src="src/paint.js?version=2021-07-05"></script>
         <script src="src/lists.js?version=2021-07-19"></script>
-        <script src="src/byob.js?version=2021-10-07"></script>
+        <script src="src/byob.js?version=2021-10-12"></script>
         <script src="src/tables.js?version=2021-05-07"></script>
         <script src="src/sketch.js?version=2021-07-05"></script>
         <script src="src/video.js?version=2019-06-27"></script>
diff --git a/src/byob.js b/src/byob.js
index 6ae137a5..6809bdca 100644
--- a/src/byob.js
+++ b/src/byob.js
@@ -108,7 +108,7 @@ WatcherMorph, XML_Serializer, SnapTranslator, SnapExtensions*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.byob = '2021-October-07';
+modules.byob = '2021-October-12';
 
 // Declarations
 
@@ -4561,8 +4561,15 @@ BlockVisibilityDialogMorph.prototype.popUp
 
 // BlockVisibilityDialogMorph menu
 
-BlockVisibilityDialogMorph.prototype.userMenu
-    = BlockExportDialogMorph.prototype.userMenu;
+BlockVisibilityDialogMorph.prototype.userMenu = function () {
+    var menu = new MenuMorph(this, 'select');
+    menu.addItem('all', 'selectAll');
+    menu.addItem('none', 'selectNone');
+    menu.addLine();
+    menu.addItem('unused', 'selectUnused');
+    return menu;
+};
+
 
 BlockVisibilityDialogMorph.prototype.selectAll = function () {
     this.selection = this.blocks.slice(0);
@@ -4578,6 +4585,43 @@ BlockVisibilityDialogMorph.prototype.selectNone = function () {
     });
 };
 
+BlockVisibilityDialogMorph.prototype.selectUnused = function () {
+    var used = this.target.scripts.allChildren().filter(
+            m => m instanceof BlockMorph),
+        uPrim = [],
+        uCust = [],
+        uVars = [];
+
+    used.forEach(b => {
+        if (b.isCustomBlock) {
+            uCust.push(b.isGlobal ? b.definition
+                : this.target.getMethod(b.semanticSpec));
+        } else if (b.selector === 'reportGetVar') {
+            uVars.push(b.blockSpec);
+        } else {
+            uPrim.push(b.selector);
+        }
+    });
+
+    this.selection = this.blocks.filter(b => {
+        if (b.isCustomBlock) {
+            return !contains(
+                uCust,
+                b.isGlobal ? b.definition
+                    : this.target.getMethod(b.semanticSpec)
+                );
+        } else if (b.selector === 'reportGetVar') {
+            return !contains(uVars, b.blockSpec);
+        } else {
+            return !contains(uPrim, b.selector);
+        }
+    });
+
+    this.body.contents.children.forEach(checkBox => {
+        checkBox.refresh();
+    });
+};
+
 // BlockVisibilityDialogMorph ops
 
 BlockVisibilityDialogMorph.prototype.hideBlocks = function () {