diff --git a/HISTORY.md b/HISTORY.md
index 5b4b5999..36172919 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -23,7 +23,8 @@
 * blocks: removed scaffolding
 * threads: removed scaffolding
 * renamed help screens for addition and multiplication blocks
-* removed now redundant variadic reporters from the variadic reporters library 
+* removed now redundant variadic reporters from the variadic reporters library
+* added dev warning box
 
 ### 2022-02-28
 * blocks, objects, threads, store: made addition reporter variadic
diff --git a/snap.html b/snap.html
index a18b2871..d42503b0 100755
--- a/snap.html
+++ b/snap.html
@@ -20,7 +20,7 @@
         <script src="src/threads.js?version=2022-03-01"></script>
         <script src="src/objects.js?version=2022-03-01"></script>
         <script src="src/scenes.js?version=2021-11-24"></script>
-        <script src="src/gui.js?version=2022-02-27"></script>
+        <script src="src/gui.js?version=2022-03-01"></script>
         <script src="src/paint.js?version=2021-07-05"></script>
         <script src="src/lists.js?version=2022-02-07"></script>
         <script src="src/byob.js?version=2022-02-17"></script>
diff --git a/src/gui.js b/src/gui.js
index db7abe11..943fdfc1 100644
--- a/src/gui.js
+++ b/src/gui.js
@@ -86,7 +86,7 @@ BlockVisibilityDialogMorph, ThreadManager*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.gui = '2022-February-27';
+modules.gui = '2022-March-01';
 
 // Declarations
 
@@ -688,6 +688,7 @@ IDE_Morph.prototype.openIn = function (world) {
 
     world.keyboardFocus = this.stage;
     this.warnAboutIE();
+    this.warnAboutDev();
 };
 
 // IDE_Morph construction
@@ -7456,6 +7457,36 @@ IDE_Morph.prototype.isIE = function () {
     return ua.indexOf("MSIE ") > -1 || ua.indexOf("Trident/") > -1;
 };
 
+// IDE_Morph warn about saving project in the dev version
+
+IDE_Morph.prototype.warnAboutDev = function () {
+    var dlg, txt;
+    dlg = new DialogBoxMorph();
+    txt = new TextMorph(
+        'This version of Snap! is being developed.\n' +
+            '*** It is NOT supported for end users. ***\n' +
+            'Saving a project in THIS version is likely to\n' +
+            'make it UNUSABLE or DEFECTIVE for current and\n' +
+            'even future official versions!',
+        dlg.fontSize,
+        dlg.fontStyle,
+        true,
+        false,
+        'center',
+        null,
+        null,
+        MorphicPreferences.isFlat ? null : new Point(1, 1),
+        WHITE
+    );
+
+    dlg.key = 'Dev-Warning';
+    dlg.labelString = "CAUTION! Development Version";
+    dlg.createLabel();
+    dlg.addBody(txt);
+    dlg.fixLayout();
+    dlg.popUp(this.world());
+};
+
 // ProjectDialogMorph ////////////////////////////////////////////////////
 
 // ProjectDialogMorph inherits from DialogBoxMorph: