DarkTaskDialog-Native

Win32 TaskDialogIndirect with complete dark mode support — zero dependencies · zero hooks · documented APIs only · MIT licensed. Windows 10 (UIA + subclassing + owner-draw) and Windows 11 (native DarkMode_TaskDialog panels + owner-drawn text).

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Screenshots

Progress dialog	Expando	Expando + footer	Command links	Rtl + Nave

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The only other public solution — SFTRS/DarkTaskDialog — hooks DrawTheme* APIs via Microsoft Detours. That requires a third-party build dependency and is GPL-3.0 licensed.

This library uses UI Automation, window subclassing, UxTheme, and DrawThemeTextEx — all fully documented Win32 APIs — and adds features the Detours approach cannot support:

	SFTRS/DarkTaskDialog	DarkTaskDialog-Native
Dependency	Microsoft Detours	None
Approach	DrawTheme* API hooking	UIA + subclassing + UxTheme
Documented APIs only	✅	✅
License	GPL-3.0	MIT

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Quick start

Requirements

	Version
Windows SDK	10.0.19041+
Visual Studio	2022 (v143)
C++ standard	C++17
Target OS	Windows 10 1809+ (build 17763)

Integration

1. Copy DarkMode.h and DarkMode.cpp into your project.

2. Call once at startup, before any windows are created:

#include "DarkMode.h"

int WINAPI wWinMain(HINSTANCE, HINSTANCE, LPWSTR, int)
{
    CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);
    DarkMode::Init();   // reads OS dark-mode state; safe no-op on pre-Win10
    // ...
}

3. Add two lines to your TaskDialogIndirect callback:

static HRESULT CALLBACK MyCallback(
    HWND hwnd, UINT note, WPARAM wParam, LPARAM lParam, LONG_PTR dwRef)
{
    auto* pCfg = reinterpret_cast<TASKDIALOGCONFIG*>(dwRef);
    switch (note)
    {
    case TDN_CREATED:
        DarkMode::AllowForTaskDialog(hwnd, pCfg);  // ← applies dark mode
        break;
    case TDN_NAVIGATED:
        // Required when using TDM_NAVIGATE_PAGE
        DarkMode::AllowForTaskDialog(hwnd, reinterpret_cast<TASKDIALOGCONFIG*>(lParam));
        break;
    case TDN_DESTROYED:
        DarkMode::RemoveFromTaskDialog(hwnd);       // ← frees per-dialog state
        break;
    }
    return S_OK;
}

TASKDIALOGCONFIG cfg = { sizeof(cfg) };
cfg.pfCallback     = MyCallback;
cfg.lpCallbackData = (LONG_PTR)&cfg;
TaskDialogIndirect(&cfg, &nButton, nullptr, nullptr);

If the system is in light mode every call is a no-op. If the user switches themes while the dialog is open it adapts automatically.

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API reference

namespace DarkMode
{
    // Call once at startup. Reads OS theme state.
    bool Init();

    // True when the OS is currently in dark mode.
    bool IsActive();

    // True on Windows 11 where DarkMode_TaskDialog UxTheme class exists.
    bool HasNativeTaskDialogTheme();

    // Sets DWMWA_USE_IMMERSIVE_DARK_MODE on a top-level window (dark title bar).
    void EnableForTLW(HWND hwnd);

    // Applies SetWindowTheme to any child control.
    void AllowForWindow(HWND hwnd, const wchar_t* themeClass = nullptr);

    // Main entry point. Call from TDN_CREATED (and TDN_NAVIGATED for page nav).
    void AllowForTaskDialog(HWND hwndTaskDialog, TASKDIALOGCONFIG* pConfig);

    // Call from TDN_DESTROYED to free per-dialog state.
    void RemoveFromTaskDialog(HWND hwndTaskDialog);
}

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How it works

The comctl32 UIFILE bug — why text needs owner-draw on every Windows version

The TaskDialog layout engine reads its colours from a stylesheet embedded in comctl32.dll as resource 4255 (UIFILE). Every text element in that stylesheet queries colour via:

foreground="gtc(TaskDialogStyle, <part>, 0, 3803)"

The key is the class name: TaskDialogStyle — not DarkMode_TaskDialogStyle. DarkMode_TaskDialogStyle does not exist in any shipping version of Windows. Because TaskDialogStyle always returns light-mode colours, every text element paints black-on-dark even when the panel backgrounds are correctly dark.

Windows 11

1- DarkMode_TaskDialog does exist — it covers all panel backgrounds and the expando glyph. AllowForTaskDialog walks the DirectUIHWND child tree by its AutomationId, calls SetWindowTheme(pane, L"DarkMode_TaskDialog", nullptr) 2- Text is then owner-drawn to fix the TaskDialogStyle colour bug described above.

Windows 10 (build 17763–19045)

DarkMode_TaskDialog does not exist. The library:

1. Uses UI Automation to walk the DirectUIHWND child tree, identifying each element by its AutomationId (the UIFILE atom names).
2. Owner-draws all elements.

Element	Windows 10	Windows 11
PrimaryPanel background	WM_ERASEBKGND dark brush	dtb(DarkMode_TaskDialog, 1, 0) ✅
SecondaryPanel background	WM_ERASEBKGND dark brush	dtb(DarkMode_TaskDialog, 8, 0) ✅
FootnoteArea background	WM_ERASEBKGND dark brush	dtb(DarkMode_TaskDialog, 15, 0) ✅
SeparatorLine background	dark brush	dtb(DarkMode_TaskDialog, 17, 0) ✅
Expando glyph	dtb(TaskDialog, 13, state)	dtb(DarkMode_TaskDialog, 13, state) ✅
All text (gtc(TaskDialogStyle,*,*))	FillRect + DrawThemeTextEx + DTT_TEXTCOLOR	DrawThemeText + DTT_TEXTCOLOR

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UIA element reference

These AutomationId strings come directly from the comctl32 UIFILE (resource 4255, Windows 11 build 26100.7965). They are the atom names the DirectUI engine uses internally and are exactly what IUIAutomationElement::get_CurrentAutomationId returns when walking the DirectUIHWND tree.

This is the only public cross-reference of these identifiers against their UxTheme part IDs and resolved dark-mode colour values.

Root

AutomationId	Description
"TaskDialog"	The DirectUIHWND TaskPage window — UIA walk entry point

Primary panel

AutomationId	UIFILE atom	Control type	UxTheme query	Dark colour
MainIcon	atom(MainIcon)	Image	—	No recolour
MainInstruction	atom(MainInstruction)	Text	gtc(TaskDialogStyle, 2, 0, 3803)	RGB(153, 235, 255)
ContentText	atom(ContentText)	Text	gtc(TaskDialogStyle, 4, 0, 3803)	RGB(255, 255, 255)
ContentLink	atom(ContentLink)	Hyperlink	gtc(TaskDialogStyle, 4, 0, 3803) + dtb(TaskDialog,1,0) bg	RGB(255, 255, 255)
ExpandedInformationText	atom(ExpandedInformationText)	Text	gtc(TaskDialogStyle, 6, 0, 3803)	RGB(255, 255, 255)
ExpandedInformationLink	atom(ExpandedInformationLink)	Hyperlink	gtc(TaskDialogStyle, 6, 0, 3803) + dtb(TaskDialog,1,0) bg	RGB(255, 255, 255)
ExpandoButton	atom(ExpandoButton)	Button	dtb(TaskDialog, 13, state)	Owner-drawn glyph
ExpandoTextExpanded	atom(ExpandoTextExpanded)	Text	gtc(TaskDialogStyle, 12, 0, 3803)	RGB(255, 255, 255)
ExpandoTextCollapsed	atom(ExpandoTextCollapsed)	Text	gtc(TaskDialogStyle, 12, 0, 3803)	RGB(255, 255, 255)
VerificationCheckBox	atom(VerificationCheckBox)	CheckBox	—	System-themed
VerificationText	atom(VerificationText)	Text	gtc(TaskDialogStyle, 14, 0, 3803)	RGB(255, 255, 255)
RadioButton_0 … _N	class RadioButton	RadioButton	dtb(TaskDialog, 1, 0) bg	System-themed
CommandLink_0 … _N	class CommandLink	Button	dtb(TaskDialog, 1, 0) bg	DarkMode_Explorer theme
CommandButton_0 … _N	class CommandButton	Button	—	DarkMode_Explorer theme
ProgressBar	atom(ProgressBar)	ProgressBar	—	System-themed

Secondary panel (button row)

AutomationId	UIFILE atom	UxTheme query	Dark colour
(push buttons)	class CommandButton	dtb(TaskDialog, 8, 0) bg	DarkMode_Explorer / DarkMode_CFD
ButtonArea	atom(ButtonArea)	gtc(TaskDialogStyle, **15**, 0, 3803) ⚠️	Uses footnote part — UIFILE quirk

Separator

AutomationId	UIFILE atom	UxTheme query	Dark colour
Separator	atom(Separator)	dtb(TaskDialog, 15, 0) bg	RGB(44, 44, 44)
SeparatorLine	atom(SeparatorLine)	dtb(TaskDialog, 17, 0) bg	RGB(77, 77, 77)

Footnote / expanded footer panel

AutomationId	UIFILE atom	UxTheme query	Dark colour
FootnoteIcon	atom(FootnoteIcon)	—	No recolour
FootnoteText	atom(FootnoteText)	gtc(TaskDialogStyle, 15, 0, 3803)	RGB(224, 224, 224)
FootnoteTextLink	atom(FootnoteTextLink)	gtc(TaskDialogStyle, 15, 0, 3803)	RGB(224, 224, 224)
ExpandedFooterText	atom(ExpandedFooterText)	gtc(TaskDialogStyle, 18, 0, 3803)	RGB(224, 224, 224)
ExpandedFooterTextLink	atom(ExpandedFooterTextLink)	gtc(TaskDialogStyle, **4**, 0, 3803) ⚠️	RGB(224, 224, 224)

⚠️ ExpandedFooterTextLink uses part 4 (the content text part) instead of part 18 in the UIFILE. This is a Microsoft bug — the wrong part ID is hardcoded. The library handles this by checking the AutomationId and applying part-18 colours regardless of what gtc() returns.

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FAQ

Does this work with the simple TaskDialog() overload? TaskDialog() has no callback, so there is no TDN_CREATED hook point. Use TaskDialogIndirect() with a TASKDIALOGCONFIG.

Does TDM_NAVIGATE_PAGE work? Yes — call DarkMode::AllowForTaskDialog(hwnd, pNewConfig) from TDN_NAVIGATED. The included main.cpp demonstrates page navigation to an Arabic RTL page.

I see a white flash when the dialog first opens. Ensure DarkMode::AllowForTaskDialog is called from TDN_CREATED, not TDN_DIALOG_CONSTRUCTED. TDN_CREATED fires after the window is fully initialised.

Can I use this from MFC? Yes — no MFC dependency. Override DoMessageBox and call TaskDialogIndirect directly. DarkMode::Init() can go in InitInstance.

Related

Tools

• memoarfaa/TaskDialog-Stylesheet-Dumper — Win32 tool that extracts and parses comctl32.dll resource 4255 (UIFILE) at runtime, then evaluates every gtf(), gtc(), gtmar(), gtmet(), and dtb() call live against OpenThemeData(L"TaskDialog") and OpenThemeData(L"TaskDialogStyle"). The resolved colour table and UIFILE bug findings documented in this README were produced with this tool. Uses only IXmlReader, FindResourceW, and GetThemeColor — no third-party dependencies. Output can be saved as XML.

Other implementations

• SFTRS/DarkTaskDialog — alternative approach using Microsoft Detours to hook DrawTheme* APIs (GPL-3.0)

References

• Stack Overflow #79403975: Dark Mode Task Dialog
• TaskDialogIndirect — Win32 docs

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License

MIT — see LICENSE.