Native dialogs on Windows are auto-closing

[benjiecalvez025-cell]

Type: Bug

in my situation the sign out dialog help > about modal dialog it can trigger immediately stops the dialog and at the same time the windows sound + ding

VS Code version: Code 1.132.0 (df53daa, 2026-08-04T15:30:20Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

Item	Value
CPUs	11th Gen Intel(R) Core(TM) i5-1145G7 @ 2.60GHz (8 x 1498)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x8086, DEVICE=0x9a49 [Intel(R) Iris(R) Xe Graphics], DRIVER_VENDOR=Intel, DRIVER_VERSION=32.0.101.7088 ACTIVE GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8875 Machine model name: Machine model version: direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	7.39GB (1.07GB free)
Process Argv	--crash-reporter-id fb5d7c07-b3fa-42e9-a1b7-ef5f40e9dd12
Screen Reader	no
VM	0%

Extensions (20)

Name	Identifier	Author	Version
Claude Code for VS Code	anthropic.claude-code	Anthropic	2.1.226
BLACKBOXAI #1 AI Coding Agent and Coding Copilot	blackboxapp.blackbox	Blackboxapp	2.8.53
Blackbox Agent - Coding Copilot	blackboxapp.blackboxagent	Blackboxapp	3.7.0
npm Intellisense	christian-kohler.npm-intellisense	christian-kohler	1.4.5
ESLint	dbaeumer.vscode-eslint	dbaeumer	3.0.34
Composer	devsense.composer-php-vscode	DEVSENSE	1.72.19127
IntelliPHP - AI Autocomplete for PHP	devsense.intelli-php-vscode	DEVSENSE	0.12.17700
PHP	devsense.phptools-vscode	DEVSENSE	1.72.19127
PHP Profiler	devsense.profiler-php-vscode	DEVSENSE	1.72.19127
Android iOS Emulator	diemasmichiels.emulate	DiemasMichiels	1.8.2
ES7+ React/Redux/React-Native snippets	dsznajder.es7-react-js-snippets	dsznajder	4.4.3
HTML CSS Support	ecmel.vscode-html-css	ecmel	2.0.14
Prettier - Code formatter	esbenp.prettier-vscode	esbenp	12.4.0
Expo Tools	expo.vscode-expo-tools	expo	1.6.3
Gemini CLI Companion	google.gemini-cli-vscode-ide-companion	google	0.20.0
Gemini Code Assist	google.geminicodeassist	google	2.95.0
Kilo Code: AI Coding Agent, Copilot, and Autocomplete	kilocode.kilo-code	kilocode	7.4.20
Material Icon Theme	pkief.material-icon-theme	PKief	5.37.0
YAML	redhat.vscode-yaml	redhat	1.24.0
JavaScript (ES6) code snippets	xabikos.javascriptsnippets	xabikos	1.8.0

A/B Experiments

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[Witawat]

here ?

if add

"window.dialogStyle": "custom"

can open

[deepak1556]

We are unable to repro on our end, does starting the app with --disable-experiments repro the issue. Also, if you can run our bisect tool npx @vscode/vscode-bisect -q insider it will help narrow down the source of regression. Thanks!

[dmitrivMS]

I traced this through the native dialog path and repository history.

Root cause

This is the same underlying issue as electron/electron#52747. On Windows, both common file dialogs and task dialogs use the #32770 window class, and message 0x0466 has two meanings:

• CDM_GETFOLDERPATH for a common file dialog
• TDM_CLICK_BUTTON for a task dialog

Software that enhances or inspects file dialogs (for example DLP/endpoint agents) can enumerate #32770 windows and send 0x0466 with wParam = 520. When sent to an Electron message box, Windows interprets that as a click on button id 520 and immediately closes the dialog.

Electron then treats every id >= 100 as a custom button without checking the upper bound, so id 520 becomes response: 420. VS Code maps that response through its reordered button array; index 420 does not exist, so the native dialog disappears without a valid user choice.

History

I could not identify a VS Code breaking commit. The relevant release mapping is:

VS Code	Electron
1.129.0	42.6.0
1.130.0	42.6.0
1.131.0	42.7.0
1.132.0	42.7.1

Since 1.129 and 1.130 use the same Electron version, reproduction in 1.130 does not establish a VS Code regression boundary. electron/electron#52747 also reproduces the response bug on Electron 36.9.1, 42.8.1, and 43.3.0; the vulnerable conversion predates these VS Code releases. The newly visible behavior is most likely caused by software sending the conflicting Windows message.

Deterministic Insiders repro

1. Install/open the latest VS Code Insiders on Windows.
2. Ensure "window.dialogStyle": "native" is set (or remove a custom override).
3. Run Help: About and leave the native dialog open.
4. While it is visible, run this from 64-bit PowerShell with no other native dialogs open:

param(
	[string]$ProcessName = 'Code - Insiders'
)

Add-Type -TypeDefinition @'
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;

public sealed class NativeDialogWindow
{
    public IntPtr Handle { get; set; }
    public uint ProcessId { get; set; }
    public string Title { get; set; }
}

public static class NativeDialogProbe
{
    private delegate bool EnumWindowsProc(IntPtr handle, IntPtr parameter);

    [DllImport("user32.dll")]
    private static extern bool EnumWindows(EnumWindowsProc callback, IntPtr parameter);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern int GetClassNameW(IntPtr handle, StringBuilder className, int maxCount);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern int GetWindowTextW(IntPtr handle, StringBuilder title, int maxCount);

    [DllImport("user32.dll")]
    private static extern uint GetWindowThreadProcessId(IntPtr handle, out uint processId);

    [DllImport("user32.dll")]
    private static extern IntPtr SendMessageW(IntPtr handle, uint message, IntPtr wParam, IntPtr lParam);

    public static NativeDialogWindow[] Find(uint[] processIds)
    {
        var matches = new List<NativeDialogWindow>();
        var expectedProcessIds = new HashSet<uint>(processIds);

        EnumWindows((handle, parameter) =>
        {
            var className = new StringBuilder(256);
            GetClassNameW(handle, className, className.Capacity);
            if (className.ToString() != "#32770")
            {
                return true;
            }

            uint processId;
            GetWindowThreadProcessId(handle, out processId);
            if (!expectedProcessIds.Contains(processId))
            {
                return true;
            }

            var title = new StringBuilder(512);
            GetWindowTextW(handle, title, title.Capacity);
            matches.Add(new NativeDialogWindow
            {
                Handle = handle,
                ProcessId = processId,
                Title = title.ToString()
            });
            return true;
        }, IntPtr.Zero);

        return matches.ToArray();
    }

    public static void Trigger(IntPtr handle)
    {
        var buffer = Marshal.AllocHGlobal(520);
        try
        {
            SendMessageW(handle, 0x0466, new IntPtr(520), buffer);
        }
        finally
        {
            Marshal.FreeHGlobal(buffer);
        }
    }
}
'@

$processIds = @(Get-Process -Name $ProcessName -ErrorAction Stop | ForEach-Object { [uint32]$_.Id })
$dialogs = @([NativeDialogProbe]::Find($processIds))

$dialogs | Format-Table Handle, ProcessId, Title -AutoSize
if ($dialogs.Count -ne 1) {
	throw "Expected exactly one native dialog owned by '$ProcessName', found $($dialogs.Count). Close other native dialogs and retry."
}

[NativeDialogProbe]::Trigger($dialogs[0].Handle)

Current behavior: the native About dialog closes immediately. The same probe can be used with a confirmation dialog such as sign out.

I have a mitigation prepared that detects the unexpected native response, maps it to the configured Cancel action for main-process callers, and retries renderer dialogs with VS Code's existing custom dialog implementation. Focused tests cover Electron's response: 420 path.

[dmitrivMS]

SteVen Batten (@sbatten) Robo (@deepak1556) FYI - verified the repro above works.