From c540c0912d2c5baef8d2784f32875dfc083d1330 Mon Sep 17 00:00:00 2001
From: Fred Sauer <fredsa@google.com>
Date: Wed, 18 Feb 2026 19:39:34 -0800
Subject: [PATCH] undoStep() CM5 -> CM6

---
 src/ide/views/editors.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/ide/views/editors.ts b/src/ide/views/editors.ts
index d5b5615c..87898d08 100644
--- a/src/ide/views/editors.ts
+++ b/src/ide/views/editors.ts
@@ -1,5 +1,5 @@
 import { closeBrackets, deleteBracketPair } from "@codemirror/autocomplete";
-import { defaultKeymap, history, historyKeymap, indentWithTab } from "@codemirror/commands";
+import { defaultKeymap, history, historyKeymap, indentWithTab, undo } from "@codemirror/commands";
 import { cpp } from "@codemirror/lang-cpp";
 import { markdown } from "@codemirror/lang-markdown";
 import { bracketMatching, foldGutter, indentOnInput, indentUnit } from "@codemirror/language";
@@ -535,7 +535,7 @@ export class SourceEditor implements ProjectView {
   }
 
   undoStep() {
-    this.editor.execCommand('undo');
+    undo(this.editor);
   }
 
   toggleBreakpoint(lineno: number) {