diff --git a/platform/mv3/extension/js/mode-editor.js b/platform/mv3/extension/js/mode-editor.js
index 3fc527eff..e88f54411 100644
--- a/platform/mv3/extension/js/mode-editor.js
+++ b/platform/mv3/extension/js/mode-editor.js
@@ -31,6 +31,11 @@ import { sendMessage } from './ext.js';
 export class ModeEditor {
     constructor(editor) {
         this.editor = editor;
+        this.bc = null;
+    }
+
+    on() {
+        if ( this.bc !== null ) { return; }
         this.bc = new self.BroadcastChannel('uBOL');
         this.bc.onmessage = ev => {
             const message = ev.data;
@@ -38,10 +43,16 @@ export class ModeEditor {
             if ( message.filteringModeDetails === undefined ) { return; }
             // TODO: merge with ongoing edits?
             const text = textFromModes(message.filteringModeDetails);
-            editor.setEditorText(text, true);
+            this.editor.setEditorText(text, true);
         };
     }
 
+    off() {
+        if ( this.bc === null ) { return; }
+        this.bc.onmessage = null;
+        this.bc = null;
+    }
+
     async getText() {
         const modes = await sendMessage({ what: 'getFilteringModeDetails' });
         return textFromModes(modes);