diff --git a/HISTORY.md b/HISTORY.md
index 37862039..9c4c6f36 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -7,9 +7,10 @@
 * **Notable Fixes:**
     * fixed occasional invisible error messages
 
-### 2021-06-16
+### 2021-06-17
 * extensions: added APL extension primitives
 * updated apl library
+* threads, extensions: added variable extension primitives
 
 ### 2021-06-16
 * threads: added exception handling primitives for try/catch
diff --git a/snap.html b/snap.html
index 345fe7e1..1bb575ea 100755
--- a/snap.html
+++ b/snap.html
@@ -9,7 +9,7 @@
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-01-05"></script>
         <script src="src/blocks.js?version=2021-06-15"></script>
-        <script src="src/threads.js?version=2021-06-16"></script>
+        <script src="src/threads.js?version=2021-06-17"></script>
         <script src="src/objects.js?version=2021-06-14"></script>
         <script src="src/gui.js?version=2021-06-14"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
diff --git a/src/extensions.js b/src/extensions.js
index 62848bf4..9e942ec1 100644
--- a/src/extensions.js
+++ b/src/extensions.js
@@ -28,7 +28,7 @@
 // Global settings /////////////////////////////////////////////////////
 
 /*global modules, List, StageMorph, Costume, SpeechSynthesisUtterance, Sound,
-IDE_Morph, CamSnapshotDialogMorph, SoundRecorderDialogMorph, isSnapObject*/
+IDE_Morph, CamSnapshotDialogMorph, SoundRecorderDialogMorph, isSnapObject, nop*/
 
 modules.extensions = '2021-June-17';
 
@@ -83,6 +83,11 @@ SnapExtensions.set(
     }
 );
 
+SnapExtensions.set(
+    'err_ignore',
+    nop
+);
+
 // list utils (lst_):
 
 SnapExtensions.set(
@@ -303,7 +308,7 @@ SnapExtensions.set(
     }
 );
 
-// Geo-location (geo_)
+// Geo-location (geo_):
 
 SnapExtensions.set(
     'geo_location(acc?)',
@@ -438,7 +443,7 @@ SnapExtensions.set(
     }
 );
 
-// Object properties (obj_)
+// Object properties (obj_):
 
 SnapExtensions.set(
     'obj_name(obj, name)',
@@ -460,3 +465,102 @@ SnapExtensions.set(
         }
     }
 );
+
+// Variables (var_):
+
+SnapExtensions.set(
+    'var_declare(scope, name)',
+    function (scope, name, proc) {
+        var frame;
+        proc.assertType(name, 'text');
+        if (name === '') {return; }
+        if (scope === 'script') {
+            frame = proc.context.isInCustomBlock() ?
+                        proc.homeContext.variables
+                        : proc.context.outerContext.variables;
+        } else if (scope === 'sprite') {
+            frame = this.variables;
+        } else {
+            frame = this.globalVariables();
+        }
+        if (frame.vars[name] === undefined) {
+            frame.addVar(name);
+        }
+    }
+);
+
+SnapExtensions.set(
+    'var_delete(name)',
+    function (name, proc) {
+        var local;
+        proc.assertType(name, 'text');
+        if (name === '') {return; }
+        local = proc.context.isInCustomBlock() ?
+                        proc.homeContext.variables
+                        : proc.context.outerContext.variables;
+        if (local.vars[name] !== undefined) {
+            delete local.vars[name];
+        } else if (this.deletableVariableNames().indexOf(name) > -1) {
+            this.deleteVariable(name);
+        }
+    }
+);
+
+SnapExtensions.set(
+    'var_get(name)',
+    function (name, proc) {
+        proc.assertType(name, 'text');
+        return proc.homeContext.variables.getVar(name);
+    }
+);
+
+SnapExtensions.set(
+    'var_set(name, val)',
+    function (name, val, proc) {
+        var local;
+        proc.assertType(name, 'text');
+        if (name === '') {return; }
+        local = proc.context.isInCustomBlock() ?
+                        proc.homeContext.variables
+                        : proc.context.outerContext.variables;
+        local.setVar(name, val);
+    }
+);
+
+SnapExtensions.set(
+    'var_show(name)',
+    function (name, proc) {
+        proc.doShowVar(
+            name,
+            proc.context.isInCustomBlock() ?
+                proc.homeContext
+                : proc.context.outerContext
+        );
+    }
+);
+
+SnapExtensions.set(
+    'var_hide(name)',
+    function (name, proc) {
+        proc.doHideVar(
+            name,
+            proc.context.isInCustomBlock() ?
+                proc.homeContext
+                : proc.context.outerContext
+        );
+    }
+);
+
+// IDE (ide_):
+
+SnapExtensions.set(
+    'ide_refreshpalette(name)',
+    function (name) {
+        var ide = this.parentThatIsA(IDE_Morph);
+        if (name !== 'variables') {
+            ide.flushBlocksCache(name);
+        }
+        ide.flushBlocksCache('variables'); // b/c of inheritance
+        ide.refreshPalette();
+    }
+);
diff --git a/src/threads.js b/src/threads.js
index 4184e93c..7c815a10 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -62,7 +62,7 @@ isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, BLACK,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume,
 SnapExtensions*/
 
-modules.threads = '2021-June-16';
+modules.threads = '2021-June-17';
 
 var ThreadManager;
 var Process;
@@ -1690,8 +1690,9 @@ Process.prototype.reportGetVar = function () {
     );
 };
 
-Process.prototype.doShowVar = function (varName) {
-    var varFrame = (this.context || this.homeContext).variables,
+Process.prototype.doShowVar = function (varName, context) {
+    // context is an optional start-context to be used by extensions
+    var varFrame = (context || (this.context || this.homeContext)).variables,
         stage,
         watcher,
         target,
@@ -1753,9 +1754,10 @@ Process.prototype.doShowVar = function (varName) {
     }
 };
 
-Process.prototype.doHideVar = function (varName) {
+Process.prototype.doHideVar = function (varName, context) {
     // if no varName is specified delete all watchers on temporaries
-    var varFrame = this.context.variables,
+    // context is an optional start-context to be used by extensions
+    var varFrame = (context || this.context).variables,
         stage,
         watcher,
         target,
@@ -6870,6 +6872,16 @@ Context.prototype.stackSize = function () {
     return 1 + this.parentContext.stackSize();
 };
 
+Context.prototype.isInCustomBlock = function () {
+    if (this.isCustomBlock) {
+        return true;
+    }
+    if (this.parentContext) {
+        return this.parentContext.isInCustomBlock();
+    }
+    return false;
+};
+
 // Variable /////////////////////////////////////////////////////////////////
 
 function Variable(value, isTransient) {