From 5044a9ffb6b23d37e7ab1b6ebf9185e51e945785 Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Tue, 2 Dec 2025 14:05:27 +0800
Subject: [PATCH 1/6] settings identifier

---
 dev/Interop/StoragePickers/FileOpenPicker.cpp | 10 ++++++++
 dev/Interop/StoragePickers/FileOpenPicker.h   |  4 +++
 dev/Interop/StoragePickers/FileSavePicker.cpp | 10 ++++++++
 dev/Interop/StoragePickers/FileSavePicker.h   |  4 +++
 dev/Interop/StoragePickers/FolderPicker.cpp   | 10 ++++++++
 dev/Interop/StoragePickers/FolderPicker.h     |  4 +++
 .../Microsoft.Windows.Storage.Pickers.idl     |  4 +++
 dev/Interop/StoragePickers/PickerCommon.cpp   | 25 +++++++++++++++++++
 dev/Interop/StoragePickers/PickerCommon.h     |  4 +++
 9 files changed, 75 insertions(+)

diff --git a/dev/Interop/StoragePickers/FileOpenPicker.cpp b/dev/Interop/StoragePickers/FileOpenPicker.cpp
index b61792f9ac..950a3bf32a 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.cpp
+++ b/dev/Interop/StoragePickers/FileOpenPicker.cpp
@@ -50,6 +50,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FileOpenPicker::SettingsIdentifier()
+    {
+        return m_settingsIdentifier;
+    }
+    void FileOpenPicker::SettingsIdentifier(winrt::hstring const& value)
+    {
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_settingsIdentifier = value;
+    }
     winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> FileOpenPicker::FileTypeChoices()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
@@ -86,6 +95,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
diff --git a/dev/Interop/StoragePickers/FileOpenPicker.h b/dev/Interop/StoragePickers/FileOpenPicker.h
index c5ff80bc27..de94d7e6b3 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.h
+++ b/dev/Interop/StoragePickers/FileOpenPicker.h
@@ -24,6 +24,9 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::hstring CommitButtonText();
         void CommitButtonText(winrt::hstring const& value);
 
+        winrt::hstring SettingsIdentifier();
+        void SettingsIdentifier(winrt::hstring const& value);
+
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> FileTypeFilter();
         winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> FileTypeChoices();
 
@@ -41,6 +44,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerViewMode m_viewMode{ PickerViewMode::List };
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         winrt::hstring m_commitButtonText{};
+        winrt::hstring m_settingsIdentifier{};
 
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> m_fileTypeFilter{ make<FileTypeFilterVector>() };
         winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> m_fileTypeChoices{
diff --git a/dev/Interop/StoragePickers/FileSavePicker.cpp b/dev/Interop/StoragePickers/FileSavePicker.cpp
index 7ffe72f818..4c2b2e3ef6 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.cpp
+++ b/dev/Interop/StoragePickers/FileSavePicker.cpp
@@ -46,6 +46,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FileSavePicker::SettingsIdentifier()
+    {
+        return m_settingsIdentifier;
+    }
+    void FileSavePicker::SettingsIdentifier(winrt::hstring const& value)
+    {
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_settingsIdentifier = value;
+    }
     winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> FileSavePicker::FileTypeChoices()
     {
         return m_fileTypeChoices;
@@ -95,6 +104,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFileName = m_suggestedFileName;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
diff --git a/dev/Interop/StoragePickers/FileSavePicker.h b/dev/Interop/StoragePickers/FileSavePicker.h
index 849c819819..b0dc7a7d1b 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.h
+++ b/dev/Interop/StoragePickers/FileSavePicker.h
@@ -21,6 +21,9 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring CommitButtonText();
         void CommitButtonText(hstring const& value);
 
+        winrt::hstring SettingsIdentifier();
+        void SettingsIdentifier(winrt::hstring const& value);
+
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> FileTypeChoices();
 
         hstring DefaultFileExtension();
@@ -41,6 +44,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::Microsoft::UI::WindowId m_windowId{};
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         hstring m_commitButtonText{};
+        winrt::hstring m_settingsIdentifier{};
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> m_fileTypeChoices{ make<FileTypeChoicesMap>() };
         hstring m_defaultFileExtension{};
         hstring m_suggestedFolder{};
diff --git a/dev/Interop/StoragePickers/FolderPicker.cpp b/dev/Interop/StoragePickers/FolderPicker.cpp
index 5da7ab331e..4d4b0c4be9 100644
--- a/dev/Interop/StoragePickers/FolderPicker.cpp
+++ b/dev/Interop/StoragePickers/FolderPicker.cpp
@@ -48,6 +48,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FolderPicker::SettingsIdentifier()
+    {
+        return m_settingsIdentifier;
+    }
+    void FolderPicker::SettingsIdentifier(winrt::hstring const& value)
+    {
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_settingsIdentifier = value;
+    }
     hstring FolderPicker::SuggestedFolder()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
@@ -75,6 +84,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
diff --git a/dev/Interop/StoragePickers/FolderPicker.h b/dev/Interop/StoragePickers/FolderPicker.h
index 49e7c4b1f7..c26aba8bfb 100644
--- a/dev/Interop/StoragePickers/FolderPicker.h
+++ b/dev/Interop/StoragePickers/FolderPicker.h
@@ -21,6 +21,9 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring CommitButtonText();
         void CommitButtonText(hstring const& value);
 
+        winrt::hstring SettingsIdentifier();
+        void SettingsIdentifier(winrt::hstring const& value);
+
         hstring SuggestedFolder();
         void SuggestedFolder(hstring const& value);
 
@@ -35,6 +38,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerViewMode m_viewMode{ PickerViewMode::List };
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         hstring m_commitButtonText{};
+        hstring m_settingsIdentifier{};
         hstring m_suggestedFolder{};
         hstring m_suggestedStartFolder{};
         StoragePickersTelemetryHelper m_telemetryHelper{};
diff --git a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
index c71d622193..ab8a46dbfe 100644
--- a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
+++ b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
@@ -43,6 +43,7 @@ namespace Microsoft.Windows.Storage.Pickers
         Microsoft.Windows.Storage.Pickers.PickerViewMode ViewMode;
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+        String SettingsIdentifier;
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
@@ -69,6 +70,8 @@ namespace Microsoft.Windows.Storage.Pickers
 
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+        String SettingsIdentifier;
+
         Windows.Foundation.Collections.IMap<String, Windows.Foundation.Collections.IVector<String> > FileTypeChoices{ get; };
         String DefaultFileExtension;
         String SuggestedFileName;
@@ -95,6 +98,7 @@ namespace Microsoft.Windows.Storage.Pickers
         Microsoft.Windows.Storage.Pickers.PickerViewMode ViewMode;
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+        String SettingsIdentifier;
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 3ba9effe05..784aa3e915 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -392,6 +392,16 @@ namespace PickerCommon {
         }
     }
 
+    winrt::hstring PickerParameters::TryGetAppUserModelId()
+    {
+        return winrt::hstring();
+    }
+
+    winrt::hstring PickerParameters::TryGetProcessFullPath()
+    {
+        return winrt::hstring();
+    }
+
     void PickerParameters::ConfigureDialog(winrt::com_ptr<IFileDialog> dialog)
     {
         if (!IsHStringNullOrEmpty(CommitButtonText))
@@ -435,6 +445,21 @@ namespace PickerCommon {
                 check_hresult(dialog->SetFileTypeIndex(FileTypeFilterPara.size()));
             }
         }
+
+        if (!IsHStringNullOrEmpty(SettingsIdentifier))
+        {
+            auto appDistinctString = TryGetAppUserModelId();
+            if (appDistinctString.empty())
+            {
+                appDistinctString = TryGetProcessFullPath();
+            }
+            if (!appDistinctString.empty())
+            {
+                auto clientId = HashHStringToGuid(appDistinctString + L"|" + SettingsIdentifier);
+                check_hresult(dialog->SetClientGuid(clientId));
+            }
+        }
+
     }
 
     /// <summary>
diff --git a/dev/Interop/StoragePickers/PickerCommon.h b/dev/Interop/StoragePickers/PickerCommon.h
index f2bc2045ab..4845adf390 100644
--- a/dev/Interop/StoragePickers/PickerCommon.h
+++ b/dev/Interop/StoragePickers/PickerCommon.h
@@ -31,6 +31,7 @@ namespace PickerCommon {
     struct PickerParameters {
         HWND HWnd{};
         winrt::hstring CommitButtonText;
+        winrt::hstring SettingsIdentifier;
         winrt::Microsoft::Windows::Storage::Pickers::PickerLocationId SuggestedStartLocation;
         std::vector<winrt::hstring> FileTypeFilterData{};
         std::vector<COMDLG_FILTERSPEC> FileTypeFilterPara{};
@@ -51,6 +52,9 @@ namespace PickerCommon {
         void ConfigureDialog(winrt::com_ptr<IFileDialog> dialog);
         void ConfigureFileSaveDialog(winrt::com_ptr<IFileSaveDialog> dialog);
 
+        winrt::hstring TryGetAppUserModelId();
+        winrt::hstring TryGetProcessFullPath();
+
     private:
         void CaptureFilterSpec(winrt::Windows::Foundation::Collections::IVectorView<winrt::hstring> filters);
         void CaptureFilterSpec(winrt::Windows::Foundation::Collections::IMapView<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> filters);

From 18d588827231908e52cd432ac41930872123b6e4 Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Tue, 2 Dec 2025 16:40:21 +0800
Subject: [PATCH 2/6] app id and exe path

---
 dev/Interop/StoragePickers/PickerCommon.cpp | 41 ++++++++++++++++++++-
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 784aa3e915..9658175274 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -3,6 +3,7 @@
 
 #include "pch.h"
 #include "shellapi.h"
+#include <appmodel.h>
 #include "PickerCommon.h"
 #include "PickerLocalization.h"
 #include <wil/resource.h>
@@ -14,7 +15,7 @@
 #include <utility>
 #include <string_view>
 #include <cwctype>
-
+#include <vector>
 
 namespace {
 
@@ -394,11 +395,47 @@ namespace PickerCommon {
 
     winrt::hstring PickerParameters::TryGetAppUserModelId()
     {
-        return winrt::hstring();
+        UINT32 length = 0;
+        LONG rc = GetCurrentApplicationUserModelId(&length, nullptr);
+        if (rc != ERROR_INSUFFICIENT_BUFFER)
+        {
+            return winrt::hstring();
+        }
+
+        std::wstring aumid;
+        aumid.resize(length);
+        rc = GetCurrentApplicationUserModelId(&length, aumid.data());
+        if (rc != ERROR_SUCCESS)
+        {
+            return winrt::hstring();
+        }
+
+        // Remove null terminator
+        if (!aumid.empty() && aumid.back() == L'\0')
+        {
+            aumid.pop_back();
+        }
+
+        return winrt::hstring(aumid);
     }
 
     winrt::hstring PickerParameters::TryGetProcessFullPath()
     {
+        wchar_t buffer[MAX_PATH];
+        DWORD length = GetModuleFileNameW(nullptr, buffer, ARRAYSIZE(buffer));
+        if (length > 0 && length < ARRAYSIZE(buffer))
+        {
+            return winrt::hstring(buffer);
+        }
+
+        // Handle long paths
+        std::vector<wchar_t> longBuffer(32768);
+        length = GetModuleFileNameW(nullptr, longBuffer.data(), static_cast<DWORD>(longBuffer.size()));
+        if (length > 0)
+        {
+            return winrt::hstring(longBuffer.data());
+        }
+
         return winrt::hstring();
     }
 

From f66ab7434c9a95bb6eb0a7e531ff4eb99de0ca71 Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Wed, 3 Dec 2025 14:29:35 +0800
Subject: [PATCH 3/6] Title; FileTypeIndex; PickeMultipleFoldersAsync;
 Containment and Telemetries

---
 dev/Interop/StoragePickers/FileOpenPicker.cpp | 28 ++++++
 dev/Interop/StoragePickers/FileOpenPicker.h   |  9 ++
 dev/Interop/StoragePickers/FileSavePicker.cpp | 26 ++++++
 dev/Interop/StoragePickers/FileSavePicker.h   | 14 ++-
 dev/Interop/StoragePickers/FolderPicker.cpp   | 87 ++++++++++++++++++-
 dev/Interop/StoragePickers/FolderPicker.h     |  9 +-
 .../Microsoft.Windows.Storage.Pickers.idl     | 34 ++++++++
 dev/Interop/StoragePickers/PickerCommon.cpp   | 59 ++++++-------
 dev/Interop/StoragePickers/PickerCommon.h     |  3 +-
 .../StoragePickers/StoragePickersTelemetry.h  | 28 ++++++
 10 files changed, 255 insertions(+), 42 deletions(-)

diff --git a/dev/Interop/StoragePickers/FileOpenPicker.cpp b/dev/Interop/StoragePickers/FileOpenPicker.cpp
index 950a3bf32a..06147a36a4 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.cpp
+++ b/dev/Interop/StoragePickers/FileOpenPicker.cpp
@@ -50,12 +50,25 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FileOpenPicker::Title()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_title;
+    }
+    void FileOpenPicker::Title(winrt::hstring const& value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_title = value;
+    }
     winrt::hstring FileOpenPicker::SettingsIdentifier()
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         return m_settingsIdentifier;
     }
     void FileOpenPicker::SettingsIdentifier(winrt::hstring const& value)
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_settingsIdentifier = value;
     }
@@ -68,6 +81,16 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeFilter;
     }
+    int FileOpenPicker::FileTypeIndex()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_fileTypeIndex;
+    }
+    void FileOpenPicker::FileTypeIndex(int value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        m_fileTypeIndex = value;
+    }
     winrt::hstring FileOpenPicker::SuggestedFolder()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
@@ -95,10 +118,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.Title = m_title;
         parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
+        
+        // Note: the user-defined index must be written in parameters before capturing filter spec for the open picker.
+        // for the fileTypeFilter may override FileTypeIndex to select "All Files" if the index is not specified by the user.
+        parameters.FileTypeIndex = m_fileTypeIndex;
         parameters.CaptureFilterSpecData(m_fileTypeFilter.GetView(), m_fileTypeChoices.GetView());
     }
 
diff --git a/dev/Interop/StoragePickers/FileOpenPicker.h b/dev/Interop/StoragePickers/FileOpenPicker.h
index de94d7e6b3..a5afc1e3ab 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.h
+++ b/dev/Interop/StoragePickers/FileOpenPicker.h
@@ -24,12 +24,18 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::hstring CommitButtonText();
         void CommitButtonText(winrt::hstring const& value);
 
+        winrt::hstring Title();
+        void Title(winrt::hstring const& value);
+
         winrt::hstring SettingsIdentifier();
         void SettingsIdentifier(winrt::hstring const& value);
 
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> FileTypeFilter();
         winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> FileTypeChoices();
 
+        int FileTypeIndex();
+        void FileTypeIndex(int value);
+
         winrt::hstring SuggestedFolder();
         void SuggestedFolder(winrt::hstring const& value);
 
@@ -44,6 +50,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerViewMode m_viewMode{ PickerViewMode::List };
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         winrt::hstring m_commitButtonText{};
+        winrt::hstring m_title{};
         winrt::hstring m_settingsIdentifier{};
 
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> m_fileTypeFilter{ make<FileTypeFilterVector>() };
@@ -56,6 +63,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
             }()
         };
 
+        int m_fileTypeIndex{ 0 };
+
         winrt::hstring m_suggestedFolder{};
         winrt::hstring m_suggestedStartFolder{};
 
diff --git a/dev/Interop/StoragePickers/FileSavePicker.cpp b/dev/Interop/StoragePickers/FileSavePicker.cpp
index 4c2b2e3ef6..316015f105 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.cpp
+++ b/dev/Interop/StoragePickers/FileSavePicker.cpp
@@ -46,12 +46,25 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FileSavePicker::Title()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_title;
+    }
+    void FileSavePicker::Title(winrt::hstring const& value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_title = value;
+    }
     winrt::hstring FileSavePicker::SettingsIdentifier()
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         return m_settingsIdentifier;
     }
     void FileSavePicker::SettingsIdentifier(winrt::hstring const& value)
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_settingsIdentifier = value;
     }
@@ -59,6 +72,16 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeChoices;
     }
+    int FileSavePicker::FileTypeIndex()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_fileTypeIndex;
+    }
+    void FileSavePicker::FileTypeIndex(int value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        m_fileTypeIndex = value;
+    }
     hstring FileSavePicker::DefaultFileExtension()
     {
         return m_defaultFileExtension;
@@ -104,11 +127,14 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.Title = m_title;
         parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFileName = m_suggestedFileName;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
+
+        parameters.FileTypeIndex = m_fileTypeIndex;
         parameters.CaptureFilterSpecData(
             winrt::Windows::Foundation::Collections::IVectorView<winrt::hstring>{},
             m_fileTypeChoices.GetView());
diff --git a/dev/Interop/StoragePickers/FileSavePicker.h b/dev/Interop/StoragePickers/FileSavePicker.h
index b0dc7a7d1b..85eea85a2a 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.h
+++ b/dev/Interop/StoragePickers/FileSavePicker.h
@@ -21,11 +21,17 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring CommitButtonText();
         void CommitButtonText(hstring const& value);
 
-        winrt::hstring SettingsIdentifier();
-        void SettingsIdentifier(winrt::hstring const& value);
+        hstring Title();
+        void Title(hstring const& value);
+        
+        hstring SettingsIdentifier();
+        void SettingsIdentifier(hstring const& value);
 
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> FileTypeChoices();
 
+        int FileTypeIndex();
+        void FileTypeIndex(int value);
+
         hstring DefaultFileExtension();
         void DefaultFileExtension(hstring const& value);
 
@@ -44,8 +50,10 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::Microsoft::UI::WindowId m_windowId{};
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         hstring m_commitButtonText{};
-        winrt::hstring m_settingsIdentifier{};
+        hstring m_title{};
+        hstring m_settingsIdentifier{};
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> m_fileTypeChoices{ make<FileTypeChoicesMap>() };
+        int m_fileTypeIndex{ 0 };
         hstring m_defaultFileExtension{};
         hstring m_suggestedFolder{};
         hstring m_suggestedStartFolder{};
diff --git a/dev/Interop/StoragePickers/FolderPicker.cpp b/dev/Interop/StoragePickers/FolderPicker.cpp
index 4d4b0c4be9..c53a3b79de 100644
--- a/dev/Interop/StoragePickers/FolderPicker.cpp
+++ b/dev/Interop/StoragePickers/FolderPicker.cpp
@@ -48,12 +48,25 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_commitButtonText = value;
     }
+    winrt::hstring FolderPicker::Title()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_title;
+    }
+    void FolderPicker::Title(winrt::hstring const& value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        PickerCommon::ValidateStringNoEmbeddedNulls(value);
+        m_title = value;
+    }
     winrt::hstring FolderPicker::SettingsIdentifier()
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         return m_settingsIdentifier;
     }
     void FolderPicker::SettingsIdentifier(winrt::hstring const& value)
     {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
         PickerCommon::ValidateStringNoEmbeddedNulls(value);
         m_settingsIdentifier = value;
     }
@@ -84,6 +97,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         parameters.HWnd = winrt::Microsoft::UI::GetWindowFromWindowId(m_windowId);
         parameters.CommitButtonText = m_commitButtonText;
+        parameters.Title = m_title;
         parameters.SettingsIdentifier = m_settingsIdentifier;
         parameters.SuggestedFolder = m_suggestedFolder;
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
@@ -98,8 +112,6 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         auto logTelemetry{ StoragePickersTelemetry::FolderPickerPickSingleFolder::Start(m_telemetryHelper) };
 
         PickerCommon::PickerParameters parameters{};
-        parameters.AllFilesText = PickerLocalization::GetStoragePickersLocalizationText(PickerCommon::AllFilesLocalizationKey);
-
         CaptureParameters(parameters);
         
         auto cancellationToken = co_await winrt::get_cancellation_token();
@@ -141,4 +153,75 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         logTelemetry.Stop(m_telemetryHelper, true);
         co_return result;
     }
+
+    winrt::Windows::Foundation::IAsyncOperation<winrt::Windows::Foundation::Collections::IVectorView<winrt::Microsoft::Windows::Storage::Pickers::PickFolderResult>> FolderPicker::PickMultipleFoldersAsync()
+    {
+        // TODO: remove get strong reference when telementry is safe stop
+        auto lifetime{ get_strong() };
+
+        auto logTelemetry{ StoragePickersTelemetry::FolderPickerPickMultipleFolder::Start(m_telemetryHelper) };
+
+        // capture parameters to avoid using get strong referece of picker
+        PickerCommon::PickerParameters parameters{};
+        CaptureParameters(parameters);
+        
+        auto cancellationToken = co_await winrt::get_cancellation_token();
+        cancellationToken.enable_propagation(true);
+        co_await winrt::resume_background();
+
+        winrt::Windows::Foundation::Collections::IVector<winrt::Microsoft::Windows::Storage::Pickers::PickFolderResult> results{ winrt::single_threaded_vector<winrt::Microsoft::Windows::Storage::Pickers::PickFolderResult>() };
+        if (cancellationToken())
+        {
+            logTelemetry.Stop(m_telemetryHelper, true, false);
+            co_return results.GetView();
+        }
+
+        auto dialog = create_instance<IFileOpenDialog>(CLSID_FileOpenDialog, CLSCTX_INPROC_SERVER);
+
+        FILEOPENDIALOGOPTIONS dialogOptions;
+        check_hresult(dialog->GetOptions(&dialogOptions));
+        check_hresult(dialog->SetOptions(dialogOptions | FOS_PICKFOLDERS | FOS_FORCEFILESYSTEM | FOS_ALLOWMULTISELECT));
+
+        {
+            auto hr = dialog->Show(parameters.HWnd);
+            if (FAILED(hr) || cancellationToken())
+            {
+                logTelemetry.Stop(m_telemetryHelper, true, false);
+                co_return results.GetView();
+            }
+        }
+
+        winrt::com_ptr<IShellItemArray> shellItems{};
+        check_hresult(dialog->GetResults(shellItems.put()));
+
+        DWORD itemCount = 0;
+        check_hresult(shellItems->GetCount(&itemCount));
+
+        winrt::com_ptr<IShellItem> shellItem{};
+        for (DWORD i = 0; i < itemCount; i++)
+        {
+            check_hresult(shellItems->GetItemAt(i, shellItem.put()));
+            auto path = PickerCommon::GetPathFromShellItem(shellItem);
+            auto result{ make<winrt::Microsoft::Windows::Storage::Pickers::implementation::PickFolderResult>(path) };
+            results.Append(result);
+        }
+
+        bool isCancelled = false;
+        if (cancellationToken())
+        {
+            results.Clear();
+            isCancelled = true;
+        }
+        auto resultView = results.GetView();
+
+        if (results.Size() > 0)
+        {
+            logTelemetry.Stop(m_telemetryHelper, isCancelled, true);
+        }
+        else
+        {
+            logTelemetry.Stop(m_telemetryHelper, isCancelled, false);
+        }
+        co_return resultView;
+    }
 }
diff --git a/dev/Interop/StoragePickers/FolderPicker.h b/dev/Interop/StoragePickers/FolderPicker.h
index c26aba8bfb..abc82e51f1 100644
--- a/dev/Interop/StoragePickers/FolderPicker.h
+++ b/dev/Interop/StoragePickers/FolderPicker.h
@@ -21,8 +21,11 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring CommitButtonText();
         void CommitButtonText(hstring const& value);
 
-        winrt::hstring SettingsIdentifier();
-        void SettingsIdentifier(winrt::hstring const& value);
+        hstring Title();
+        void Title(hstring const& value);
+
+        hstring SettingsIdentifier();
+        void SettingsIdentifier(hstring const& value);
 
         hstring SuggestedFolder();
         void SuggestedFolder(hstring const& value);
@@ -31,6 +34,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         void SuggestedStartFolder(hstring const& value);
 
         winrt::Windows::Foundation::IAsyncOperation<winrt::Microsoft::Windows::Storage::Pickers::PickFolderResult> PickSingleFolderAsync();
+        winrt::Windows::Foundation::IAsyncOperation<winrt::Windows::Foundation::Collections::IVectorView<winrt::Microsoft::Windows::Storage::Pickers::PickFolderResult>> PickMultipleFoldersAsync();
 
     private:
         winrt::Microsoft::UI::WindowId m_windowId{};
@@ -38,6 +42,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         PickerViewMode m_viewMode{ PickerViewMode::List };
         PickerLocationId m_suggestedStartLocation{ PickerLocationId::Unspecified };
         hstring m_commitButtonText{};
+        hstring m_title{};
         hstring m_settingsIdentifier{};
         hstring m_suggestedFolder{};
         hstring m_suggestedStartFolder{};
diff --git a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
index ab8a46dbfe..b4af1514b0 100644
--- a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
+++ b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
@@ -43,6 +43,13 @@ namespace Microsoft.Windows.Storage.Pickers
         Microsoft.Windows.Storage.Pickers.PickerViewMode ViewMode;
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        String Title;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
         String SettingsIdentifier;
 
         [contract(StoragePickersContract, 2.0)]
@@ -51,6 +58,10 @@ namespace Microsoft.Windows.Storage.Pickers
 
         Windows.Foundation.Collections.IVector<String> FileTypeFilter{ get; };
 
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        UInt32 FileTypeIndex;
+
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
         String SuggestedFolder;
@@ -70,9 +81,21 @@ namespace Microsoft.Windows.Storage.Pickers
 
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        String Title;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
         String SettingsIdentifier;
 
         Windows.Foundation.Collections.IMap<String, Windows.Foundation.Collections.IVector<String> > FileTypeChoices{ get; };
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        UInt32 FileTypeIndex;
+
         String DefaultFileExtension;
         String SuggestedFileName;
         String SuggestedFolder;
@@ -98,6 +121,13 @@ namespace Microsoft.Windows.Storage.Pickers
         Microsoft.Windows.Storage.Pickers.PickerViewMode ViewMode;
         Microsoft.Windows.Storage.Pickers.PickerLocationId SuggestedStartLocation;
         String CommitButtonText;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        String Title;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
         String SettingsIdentifier;
 
         [contract(StoragePickersContract, 2.0)]
@@ -109,5 +139,9 @@ namespace Microsoft.Windows.Storage.Pickers
         String SuggestedStartFolder;
 
         [remote_sync] Windows.Foundation.IAsyncOperation<PickFolderResult> PickSingleFolderAsync();
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+        [remote_sync] Windows.Foundation.IAsyncOperation<Windows.Foundation.Collections.IVectorView<PickFolderResult> > PickMultipleFoldersAsync();
     }
 }
diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 9658175274..0a9ec98b7d 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -357,7 +357,11 @@ namespace PickerCommon {
             FileTypeFilterPara.push_back({ FileTypeFilterData.at(i * 2).c_str(), FileTypeFilterData.at(i * 2 + 1).c_str() });
         }
 
-        FocusLastFilter = true;
+        if (FileTypeIndex == 0)
+        {
+            // If the FileTypeIndex is not specified by the user, set to focuse the last one ("All Files")
+            FileTypeIndex = static_cast<int>(resultSize);
+        }
     }
 
     /// <summary>
@@ -395,48 +399,30 @@ namespace PickerCommon {
 
     winrt::hstring PickerParameters::TryGetAppUserModelId()
     {
-        UINT32 length = 0;
-        LONG rc = GetCurrentApplicationUserModelId(&length, nullptr);
-        if (rc != ERROR_INSUFFICIENT_BUFFER)
-        {
-            return winrt::hstring();
-        }
+        wchar_t appUserModelId[APPLICATION_USER_MODEL_ID_MAX_LENGTH] = {};
+        UINT32 appUserModelIdSize{ APPLICATION_USER_MODEL_ID_MAX_LENGTH };
 
-        std::wstring aumid;
-        aumid.resize(length);
-        rc = GetCurrentApplicationUserModelId(&length, aumid.data());
-        if (rc != ERROR_SUCCESS)
-        {
-            return winrt::hstring();
-        }
-
-        // Remove null terminator
-        if (!aumid.empty() && aumid.back() == L'\0')
+        auto hr{GetCurrentApplicationUserModelId(&appUserModelIdSize, appUserModelId) };
+        if (SUCCEEDED(hr))
         {
-            aumid.pop_back();
+            return winrt::hstring{ appUserModelId };
         }
 
-        return winrt::hstring(aumid);
+        return winrt::hstring{};
     }
 
     winrt::hstring PickerParameters::TryGetProcessFullPath()
     {
-        wchar_t buffer[MAX_PATH];
-        DWORD length = GetModuleFileNameW(nullptr, buffer, ARRAYSIZE(buffer));
-        if (length > 0 && length < ARRAYSIZE(buffer))
-        {
-            return winrt::hstring(buffer);
-        }
-
-        // Handle long paths
-        std::vector<wchar_t> longBuffer(32768);
-        length = GetModuleFileNameW(nullptr, longBuffer.data(), static_cast<DWORD>(longBuffer.size()));
-        if (length > 0)
+        PCWSTR exeFullPath{};
+        wil::unique_cotaskmem_string module;
+        auto hr{ LOG_IF_FAILED(wil::GetModuleFileNameW(nullptr, module)) };
+        if (SUCCEEDED(hr))
         {
-            return winrt::hstring(longBuffer.data());
+            exeFullPath = module.get();
+            return winrt::hstring{ exeFullPath };
         }
 
-        return winrt::hstring();
+        return winrt::hstring{};
     }
 
     void PickerParameters::ConfigureDialog(winrt::com_ptr<IFileDialog> dialog)
@@ -446,6 +432,11 @@ namespace PickerCommon {
             check_hresult(dialog->SetOkButtonLabel(CommitButtonText.c_str()));
         }
 
+        if (!IsHStringNullOrEmpty(Title))
+        {
+            check_hresult(dialog->SetTitle(Title.c_str()));
+        }
+
         winrt::com_ptr<IShellItem> defaultFolder{};
 
         // The SuggestedStartFolder takes precedence over SuggestedStartLocation if both are provided.
@@ -477,9 +468,9 @@ namespace PickerCommon {
         {
             check_hresult(dialog->SetFileTypes((UINT)FileTypeFilterPara.size(), FileTypeFilterPara.data()));
 
-            if (FocusLastFilter)
+            if (FileTypeIndex > 0 && FileTypeIndex <= static_cast<int>(FileTypeFilterPara.size()))
             {
-                check_hresult(dialog->SetFileTypeIndex(FileTypeFilterPara.size()));
+                check_hresult(dialog->SetFileTypeIndex(FileTypeIndex));
             }
         }
 
diff --git a/dev/Interop/StoragePickers/PickerCommon.h b/dev/Interop/StoragePickers/PickerCommon.h
index 4845adf390..e7ef47c5da 100644
--- a/dev/Interop/StoragePickers/PickerCommon.h
+++ b/dev/Interop/StoragePickers/PickerCommon.h
@@ -31,11 +31,12 @@ namespace PickerCommon {
     struct PickerParameters {
         HWND HWnd{};
         winrt::hstring CommitButtonText;
+        winrt::hstring Title;
         winrt::hstring SettingsIdentifier;
         winrt::Microsoft::Windows::Storage::Pickers::PickerLocationId SuggestedStartLocation;
         std::vector<winrt::hstring> FileTypeFilterData{};
         std::vector<COMDLG_FILTERSPEC> FileTypeFilterPara{};
-        bool FocusLastFilter{ false };
+        int FileTypeIndex{ 0 };
         winrt::hstring AllFilesText{ L"All Files" }; // initialize to All Files as a default value, will be updated by localization
 
         winrt::hstring SuggestedFileName;
diff --git a/dev/Interop/StoragePickers/StoragePickersTelemetry.h b/dev/Interop/StoragePickers/StoragePickersTelemetry.h
index cf116c778f..2bb72d6cd8 100644
--- a/dev/Interop/StoragePickers/StoragePickersTelemetry.h
+++ b/dev/Interop/StoragePickers/StoragePickersTelemetry.h
@@ -124,4 +124,32 @@ class StoragePickersTelemetry : public wil::TraceLoggingProvider
         }
         CATCH_LOG()
     END_ACTIVITY_CLASS();
+
+    BEGIN_COMPLIANT_CRITICAL_DATA_ACTIVITY_CLASS(FolderPickerPickMultipleFolder, PDT_ProductAndServicePerformance);
+        DEFINE_ACTIVITY_START(StoragePickersTelemetryHelper& telemetryHelper) noexcept try
+        {
+            TraceLoggingClassWriteStart(
+                FolderPickerPickMultipleFolder,
+                _GENERIC_PARTB_FIELDS_ENABLED,
+                TraceLoggingBool(telemetryHelper.IsPackagedApp(), "IsAppPackaged"),
+                TraceLoggingBool(telemetryHelper.IsRunningAsAdmin(), "IsRunningAsAdmin"),
+                TraceLoggingBool(telemetryHelper.IsRunningInContainer(), "IsRunningInContainer"),
+                TraceLoggingWideString(telemetryHelper.GetAppName().c_str(), "AppName"));
+        }
+        CATCH_LOG()
+
+        DEFINE_ACTIVITY_STOP(StoragePickersTelemetryHelper& telemetryHelper, bool const resultCancelled, bool const resultNotEmpty) noexcept try
+        {
+            TraceLoggingClassWriteStop(
+                FolderPickerPickMultipleFolder,
+                _GENERIC_PARTB_FIELDS_ENABLED,
+                TraceLoggingBool(resultCancelled, "resultCancelled"),
+                TraceLoggingBool(resultNotEmpty, "resultNotEmpty"),
+                TraceLoggingBool(telemetryHelper.IsPackagedApp(), "IsAppPackaged"),
+                TraceLoggingBool(telemetryHelper.IsRunningAsAdmin(), "IsRunningAsAdmin"),
+                TraceLoggingBool(telemetryHelper.IsRunningInContainer(), "IsRunningInContainer"),
+                TraceLoggingWideString(telemetryHelper.GetAppName().c_str(), "AppName"));
+        }
+        CATCH_LOG()
+    END_ACTIVITY_CLASS();
 };

From 3ec20e15f469c5e03e2d28157b8e2f56aa845002 Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Thu, 4 Dec 2025 16:11:38 +0800
Subject: [PATCH 4/6] adding FileSavePicker.ShowOverwritePrompt and
 FileSavePicker.CreateNewFileIfNotExists

---
 dev/Interop/StoragePickers/FileSavePicker.cpp | 31 +++++++++++++++++--
 dev/Interop/StoragePickers/FileSavePicker.h   |  8 +++++
 .../Microsoft.Windows.Storage.Pickers.idl     |  8 +++++
 dev/Interop/StoragePickers/PickerCommon.cpp   |  8 +++++
 dev/Interop/StoragePickers/PickerCommon.h     |  2 ++
 5 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/dev/Interop/StoragePickers/FileSavePicker.cpp b/dev/Interop/StoragePickers/FileSavePicker.cpp
index 316015f105..b8194cdb2e 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.cpp
+++ b/dev/Interop/StoragePickers/FileSavePicker.cpp
@@ -86,6 +86,26 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_defaultFileExtension;
     }
+    bool FileSavePicker::ShowOverwritePrompt()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_showOverwritePrompt;
+	}
+	void FileSavePicker::ShowOverwritePrompt(bool value)
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+		m_showOverwritePrompt = value;
+	}
+    bool FileSavePicker::CreateNewFileIfNotExists()
+    {
+        THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+        return m_createNewFileIfNotExists;
+	}
+    void FileSavePicker::CreateNewFileIfNotExists(bool value)
+    {
+		THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
+		m_createNewFileIfNotExists = value;
+	}
     void FileSavePicker::DefaultFileExtension(hstring const& value)
     {
         m_defaultFileExtension = value;
@@ -138,6 +158,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         parameters.CaptureFilterSpecData(
             winrt::Windows::Foundation::Collections::IVectorView<winrt::hstring>{},
             m_fileTypeChoices.GetView());
+		parameters.ShowOverwritePrompt = m_showOverwritePrompt;
     }
 
     winrt::Windows::Foundation::IAsyncOperation<winrt::Microsoft::Windows::Storage::Pickers::PickFileResult> FileSavePicker::PickSaveFileAsync()
@@ -207,9 +228,13 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         check_hresult(shellItem->GetDisplayName(SIGDN_NORMALDISPLAY, fileName.put()));
         std::wstring fileNameStr(fileName.get());
 
-        // Create an empty file if the file doesn't exist,
-        // If the file already exists, do nothing.
-        auto [handle, _] = wil::try_open_or_create_file(pathStr.c_str(), GENERIC_WRITE);
+        // Feature_StoragePickers2 gives the option to skip creating the picked file when it doesn't exist.
+        if (m_createNewFileIfNotExists || !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled())
+        {
+            // Create an empty file if the file doesn't exist,
+            // If the file already exists, do nothing.
+            auto [handle, _] = wil::try_open_or_create_file(pathStr.c_str(), GENERIC_WRITE);
+        }
 
         if (cancellationToken())
         {
diff --git a/dev/Interop/StoragePickers/FileSavePicker.h b/dev/Interop/StoragePickers/FileSavePicker.h
index 85eea85a2a..e6a517af61 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.h
+++ b/dev/Interop/StoragePickers/FileSavePicker.h
@@ -35,6 +35,12 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring DefaultFileExtension();
         void DefaultFileExtension(hstring const& value);
 
+		bool ShowOverwritePrompt();
+		void ShowOverwritePrompt(bool value);
+
+		bool CreateNewFileIfNotExists();
+		void CreateNewFileIfNotExists(bool value);
+
         hstring SuggestedFolder();
         void SuggestedFolder(hstring const& value);
 
@@ -55,6 +61,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> m_fileTypeChoices{ make<FileTypeChoicesMap>() };
         int m_fileTypeIndex{ 0 };
         hstring m_defaultFileExtension{};
+		bool m_showOverwritePrompt{ true };
+		bool m_createNewFileIfNotExists{ true };
         hstring m_suggestedFolder{};
         hstring m_suggestedStartFolder{};
         hstring m_suggestedFileName{};
diff --git a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
index b4af1514b0..aad1adae97 100644
--- a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
+++ b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
@@ -104,6 +104,14 @@ namespace Microsoft.Windows.Storage.Pickers
         [feature(Feature_StoragePickers2)]
         String SuggestedStartFolder;
 
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+		Boolean ShowOverwritePrompt;
+
+        [contract(StoragePickersContract, 2.0)]
+        [feature(Feature_StoragePickers2)]
+		Boolean CreateNewFileIfNotExists;
+
         [remote_sync] Windows.Foundation.IAsyncOperation<PickFileResult> PickSaveFileAsync();
     }
 
diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 0a9ec98b7d..2883200a9c 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -501,5 +501,13 @@ namespace PickerCommon {
             check_hresult(dialog->SetFileName(SuggestedFileName.c_str()));
         }
 
+        if (!ShowOverwritePrompt)
+        {
+            FILEOPENDIALOGOPTIONS options{};
+            check_hresult(dialog->GetOptions(&options));
+            options = static_cast<FILEOPENDIALOGOPTIONS>(options & ~FOS_OVERWRITEPROMPT);
+			check_hresult(dialog->SetOptions(options));
+        }
+
     }
 }
diff --git a/dev/Interop/StoragePickers/PickerCommon.h b/dev/Interop/StoragePickers/PickerCommon.h
index e7ef47c5da..cf53210662 100644
--- a/dev/Interop/StoragePickers/PickerCommon.h
+++ b/dev/Interop/StoragePickers/PickerCommon.h
@@ -56,6 +56,8 @@ namespace PickerCommon {
         winrt::hstring TryGetAppUserModelId();
         winrt::hstring TryGetProcessFullPath();
 
+		bool ShowOverwritePrompt;
+
     private:
         void CaptureFilterSpec(winrt::Windows::Foundation::Collections::IVectorView<winrt::hstring> filters);
         void CaptureFilterSpec(winrt::Windows::Foundation::Collections::IMapView<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> filters);

From 8b758b12772bef29867c972184edbb744cbee58f Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Wed, 10 Dec 2025 15:40:44 +0800
Subject: [PATCH 5/6] rename to DefaultFileTypeIndex; 0-based

---
 dev/Interop/StoragePickers/FileOpenPicker.cpp        | 12 ++++++------
 dev/Interop/StoragePickers/FileOpenPicker.h          |  6 +++---
 dev/Interop/StoragePickers/FileSavePicker.cpp        | 10 +++++-----
 dev/Interop/StoragePickers/FileSavePicker.h          |  6 +++---
 .../Microsoft.Windows.Storage.Pickers.idl            |  4 ++--
 dev/Interop/StoragePickers/PickerCommon.cpp          | 10 +++++-----
 dev/Interop/StoragePickers/PickerCommon.h            |  2 +-
 7 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/dev/Interop/StoragePickers/FileOpenPicker.cpp b/dev/Interop/StoragePickers/FileOpenPicker.cpp
index 06147a36a4..0fb8c36232 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.cpp
+++ b/dev/Interop/StoragePickers/FileOpenPicker.cpp
@@ -81,15 +81,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeFilter;
     }
-    int FileOpenPicker::FileTypeIndex()
+    int FileOpenPicker::DefaultFileTypeIndex()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        return m_fileTypeIndex;
+        return m_defaultFileTypeIndex;
     }
-    void FileOpenPicker::FileTypeIndex(int value)
+    void FileOpenPicker::DefaultFileTypeIndex(int value)
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        m_fileTypeIndex = value;
+        m_defaultFileTypeIndex = value;
     }
     winrt::hstring FileOpenPicker::SuggestedFolder()
     {
@@ -125,8 +125,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
         
         // Note: the user-defined index must be written in parameters before capturing filter spec for the open picker.
-        // for the fileTypeFilter may override FileTypeIndex to select "All Files" if the index is not specified by the user.
-        parameters.FileTypeIndex = m_fileTypeIndex;
+        // for the fileTypeFilter may override DefaultFileTypeIndex to select "All Files" if the index is not specified by the user.
+        parameters.DefaultFileTypeIndex = m_defaultFileTypeIndex;
         parameters.CaptureFilterSpecData(m_fileTypeFilter.GetView(), m_fileTypeChoices.GetView());
     }
 
diff --git a/dev/Interop/StoragePickers/FileOpenPicker.h b/dev/Interop/StoragePickers/FileOpenPicker.h
index a5afc1e3ab..ae9b2198d9 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.h
+++ b/dev/Interop/StoragePickers/FileOpenPicker.h
@@ -33,8 +33,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> FileTypeFilter();
         winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> FileTypeChoices();
 
-        int FileTypeIndex();
-        void FileTypeIndex(int value);
+        int DefaultFileTypeIndex();
+        void DefaultFileTypeIndex(int value);
 
         winrt::hstring SuggestedFolder();
         void SuggestedFolder(winrt::hstring const& value);
@@ -63,7 +63,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
             }()
         };
 
-        int m_fileTypeIndex{ 0 };
+        int m_defaultFileTypeIndex{ -1 };
 
         winrt::hstring m_suggestedFolder{};
         winrt::hstring m_suggestedStartFolder{};
diff --git a/dev/Interop/StoragePickers/FileSavePicker.cpp b/dev/Interop/StoragePickers/FileSavePicker.cpp
index b8194cdb2e..48be5a96c5 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.cpp
+++ b/dev/Interop/StoragePickers/FileSavePicker.cpp
@@ -72,15 +72,15 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeChoices;
     }
-    int FileSavePicker::FileTypeIndex()
+    int FileSavePicker::DefaultFileTypeIndex()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        return m_fileTypeIndex;
+        return m_defaultFileTypeIndex;
     }
-    void FileSavePicker::FileTypeIndex(int value)
+    void FileSavePicker::DefaultFileTypeIndex(int value)
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        m_fileTypeIndex = value;
+        m_defaultFileTypeIndex = value;
     }
     hstring FileSavePicker::DefaultFileExtension()
     {
@@ -154,7 +154,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         parameters.SuggestedStartLocation = m_suggestedStartLocation;
         parameters.SuggestedStartFolder = m_suggestedStartFolder;
 
-        parameters.FileTypeIndex = m_fileTypeIndex;
+        parameters.DefaultFileTypeIndex = m_defaultFileTypeIndex;
         parameters.CaptureFilterSpecData(
             winrt::Windows::Foundation::Collections::IVectorView<winrt::hstring>{},
             m_fileTypeChoices.GetView());
diff --git a/dev/Interop/StoragePickers/FileSavePicker.h b/dev/Interop/StoragePickers/FileSavePicker.h
index e6a517af61..4507048baf 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.h
+++ b/dev/Interop/StoragePickers/FileSavePicker.h
@@ -29,8 +29,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
 
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> FileTypeChoices();
 
-        int FileTypeIndex();
-        void FileTypeIndex(int value);
+        int DefaultFileTypeIndex();
+        void DefaultFileTypeIndex(int value);
 
         hstring DefaultFileExtension();
         void DefaultFileExtension(hstring const& value);
@@ -59,7 +59,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring m_title{};
         hstring m_settingsIdentifier{};
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> m_fileTypeChoices{ make<FileTypeChoicesMap>() };
-        int m_fileTypeIndex{ 0 };
+        int m_defaultFileTypeIndex{ -1 };
         hstring m_defaultFileExtension{};
 		bool m_showOverwritePrompt{ true };
 		bool m_createNewFileIfNotExists{ true };
diff --git a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
index aad1adae97..1f03ad58e6 100644
--- a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
+++ b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
@@ -60,7 +60,7 @@ namespace Microsoft.Windows.Storage.Pickers
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
-        UInt32 FileTypeIndex;
+        Int32 DefaultFileTypeIndex;
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
@@ -94,7 +94,7 @@ namespace Microsoft.Windows.Storage.Pickers
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
-        UInt32 FileTypeIndex;
+        Int32 DefaultFileTypeIndex;
 
         String DefaultFileExtension;
         String SuggestedFileName;
diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 2883200a9c..88301c4e64 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -357,10 +357,10 @@ namespace PickerCommon {
             FileTypeFilterPara.push_back({ FileTypeFilterData.at(i * 2).c_str(), FileTypeFilterData.at(i * 2 + 1).c_str() });
         }
 
-        if (FileTypeIndex == 0)
+        if (DefaultFileTypeIndex == -1)
         {
-            // If the FileTypeIndex is not specified by the user, set to focuse the last one ("All Files")
-            FileTypeIndex = static_cast<int>(resultSize);
+            // If the DefaultFileTypeIndex is not specified by the user, set to focuse the last one ("All Files")
+            DefaultFileTypeIndex = static_cast<int>(resultSize) - 1;
         }
     }
 
@@ -468,9 +468,9 @@ namespace PickerCommon {
         {
             check_hresult(dialog->SetFileTypes((UINT)FileTypeFilterPara.size(), FileTypeFilterPara.data()));
 
-            if (FileTypeIndex > 0 && FileTypeIndex <= static_cast<int>(FileTypeFilterPara.size()))
+            if (DefaultFileTypeIndex != -1 && DefaultFileTypeIndex < static_cast<int>(FileTypeFilterPara.size()))
             {
-                check_hresult(dialog->SetFileTypeIndex(FileTypeIndex));
+                check_hresult(dialog->SetFileTypeIndex(DefaultFileTypeIndex + 1)); // COMDLG file type index is 1-based
             }
         }
 
diff --git a/dev/Interop/StoragePickers/PickerCommon.h b/dev/Interop/StoragePickers/PickerCommon.h
index cf53210662..a112323a69 100644
--- a/dev/Interop/StoragePickers/PickerCommon.h
+++ b/dev/Interop/StoragePickers/PickerCommon.h
@@ -36,7 +36,7 @@ namespace PickerCommon {
         winrt::Microsoft::Windows::Storage::Pickers::PickerLocationId SuggestedStartLocation;
         std::vector<winrt::hstring> FileTypeFilterData{};
         std::vector<COMDLG_FILTERSPEC> FileTypeFilterPara{};
-        int FileTypeIndex{ 0 };
+        int DefaultFileTypeIndex{ -1 };
         winrt::hstring AllFilesText{ L"All Files" }; // initialize to All Files as a default value, will be updated by localization
 
         winrt::hstring SuggestedFileName;

From 852aa73312202c81a36ae085867738fbd0fd293e Mon Sep 17 00:00:00 2001
From: DinahK-2SO <116714259+DinahK-2SO@users.noreply.github.com>
Date: Wed, 10 Dec 2025 16:28:36 +0800
Subject: [PATCH 6/6] nullable (IReference) DefaultFileTypeIndex

---
 dev/Interop/StoragePickers/FileOpenPicker.cpp | 20 +++++++++++++++----
 dev/Interop/StoragePickers/FileOpenPicker.h   |  7 ++++---
 dev/Interop/StoragePickers/FileSavePicker.cpp | 20 +++++++++++++++----
 dev/Interop/StoragePickers/FileSavePicker.h   |  7 ++++---
 .../Microsoft.Windows.Storage.Pickers.idl     |  4 ++--
 dev/Interop/StoragePickers/PickerCommon.cpp   |  8 ++++----
 dev/Interop/StoragePickers/PickerCommon.h     |  3 ++-
 7 files changed, 48 insertions(+), 21 deletions(-)

diff --git a/dev/Interop/StoragePickers/FileOpenPicker.cpp b/dev/Interop/StoragePickers/FileOpenPicker.cpp
index 0fb8c36232..809aedd2ef 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.cpp
+++ b/dev/Interop/StoragePickers/FileOpenPicker.cpp
@@ -81,15 +81,27 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeFilter;
     }
-    int FileOpenPicker::DefaultFileTypeIndex()
+    winrt::Windows::Foundation::IReference<uint32_t> FileOpenPicker::DefaultFileTypeIndex()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        return m_defaultFileTypeIndex;
+        if (!m_defaultFileTypeIndex.has_value())
+        {
+            return nullptr;
+        }
+
+        return winrt::box_value(*m_defaultFileTypeIndex).as<winrt::Windows::Foundation::IReference<uint32_t>>();
     }
-    void FileOpenPicker::DefaultFileTypeIndex(int value)
+    void FileOpenPicker::DefaultFileTypeIndex(winrt::Windows::Foundation::IReference<uint32_t> const& value)
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        m_defaultFileTypeIndex = value;
+        if (value)
+        {
+            m_defaultFileTypeIndex = value.Value();
+        }
+        else
+        {
+            m_defaultFileTypeIndex.reset();
+        }
     }
     winrt::hstring FileOpenPicker::SuggestedFolder()
     {
diff --git a/dev/Interop/StoragePickers/FileOpenPicker.h b/dev/Interop/StoragePickers/FileOpenPicker.h
index ae9b2198d9..556498b867 100644
--- a/dev/Interop/StoragePickers/FileOpenPicker.h
+++ b/dev/Interop/StoragePickers/FileOpenPicker.h
@@ -8,6 +8,7 @@
 #include <winrt/Windows.Foundation.Collections.h>
 #include "FileTypeChoicesMap.h"
 #include "FileTypeFilterVector.h"
+#include <optional>
 
 namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
 {
@@ -33,8 +34,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         winrt::Windows::Foundation::Collections::IVector<winrt::hstring> FileTypeFilter();
         winrt::Windows::Foundation::Collections::IMap<winrt::hstring, winrt::Windows::Foundation::Collections::IVector<winrt::hstring>> FileTypeChoices();
 
-        int DefaultFileTypeIndex();
-        void DefaultFileTypeIndex(int value);
+        winrt::Windows::Foundation::IReference<uint32_t> DefaultFileTypeIndex();
+        void DefaultFileTypeIndex(winrt::Windows::Foundation::IReference<uint32_t> const& value);
 
         winrt::hstring SuggestedFolder();
         void SuggestedFolder(winrt::hstring const& value);
@@ -63,7 +64,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
             }()
         };
 
-        int m_defaultFileTypeIndex{ -1 };
+        std::optional<uint32_t> m_defaultFileTypeIndex{};
 
         winrt::hstring m_suggestedFolder{};
         winrt::hstring m_suggestedStartFolder{};
diff --git a/dev/Interop/StoragePickers/FileSavePicker.cpp b/dev/Interop/StoragePickers/FileSavePicker.cpp
index 48be5a96c5..a9b4f922aa 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.cpp
+++ b/dev/Interop/StoragePickers/FileSavePicker.cpp
@@ -72,15 +72,27 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
     {
         return m_fileTypeChoices;
     }
-    int FileSavePicker::DefaultFileTypeIndex()
+    winrt::Windows::Foundation::IReference<uint32_t> FileSavePicker::DefaultFileTypeIndex()
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        return m_defaultFileTypeIndex;
+        if (!m_defaultFileTypeIndex.has_value())
+        {
+            return nullptr;
+        }
+
+        return winrt::box_value(*m_defaultFileTypeIndex).as<winrt::Windows::Foundation::IReference<uint32_t>>();
     }
-    void FileSavePicker::DefaultFileTypeIndex(int value)
+    void FileSavePicker::DefaultFileTypeIndex(winrt::Windows::Foundation::IReference<uint32_t> const& value)
     {
         THROW_HR_IF(E_NOTIMPL, !::Microsoft::Windows::Storage::Pickers::Feature_StoragePickers2::IsEnabled());
-        m_defaultFileTypeIndex = value;
+        if (value)
+        {
+            m_defaultFileTypeIndex = value.Value();
+        }
+        else
+        {
+            m_defaultFileTypeIndex.reset();
+        }
     }
     hstring FileSavePicker::DefaultFileExtension()
     {
diff --git a/dev/Interop/StoragePickers/FileSavePicker.h b/dev/Interop/StoragePickers/FileSavePicker.h
index 4507048baf..77a5b2d878 100644
--- a/dev/Interop/StoragePickers/FileSavePicker.h
+++ b/dev/Interop/StoragePickers/FileSavePicker.h
@@ -6,6 +6,7 @@
 #include "PickerCommon.h"
 #include "StoragePickersTelemetryHelper.h"
 #include "FileTypeChoicesMap.h"
+#include <optional>
 
 namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
 {
@@ -29,8 +30,8 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
 
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> FileTypeChoices();
 
-        int DefaultFileTypeIndex();
-        void DefaultFileTypeIndex(int value);
+        winrt::Windows::Foundation::IReference<uint32_t> DefaultFileTypeIndex();
+        void DefaultFileTypeIndex(winrt::Windows::Foundation::IReference<uint32_t> const& value);
 
         hstring DefaultFileExtension();
         void DefaultFileExtension(hstring const& value);
@@ -59,7 +60,7 @@ namespace winrt::Microsoft::Windows::Storage::Pickers::implementation
         hstring m_title{};
         hstring m_settingsIdentifier{};
         winrt::Windows::Foundation::Collections::IMap<hstring, winrt::Windows::Foundation::Collections::IVector<hstring>> m_fileTypeChoices{ make<FileTypeChoicesMap>() };
-        int m_defaultFileTypeIndex{ -1 };
+        std::optional<uint32_t> m_defaultFileTypeIndex{};
         hstring m_defaultFileExtension{};
 		bool m_showOverwritePrompt{ true };
 		bool m_createNewFileIfNotExists{ true };
diff --git a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
index 1f03ad58e6..542ee3da23 100644
--- a/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
+++ b/dev/Interop/StoragePickers/Microsoft.Windows.Storage.Pickers.idl
@@ -60,7 +60,7 @@ namespace Microsoft.Windows.Storage.Pickers
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
-        Int32 DefaultFileTypeIndex;
+        Windows.Foundation.IReference<UInt32> DefaultFileTypeIndex;
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
@@ -94,7 +94,7 @@ namespace Microsoft.Windows.Storage.Pickers
 
         [contract(StoragePickersContract, 2.0)]
         [feature(Feature_StoragePickers2)]
-        Int32 DefaultFileTypeIndex;
+        Windows.Foundation.IReference<UInt32> DefaultFileTypeIndex;
 
         String DefaultFileExtension;
         String SuggestedFileName;
diff --git a/dev/Interop/StoragePickers/PickerCommon.cpp b/dev/Interop/StoragePickers/PickerCommon.cpp
index 88301c4e64..0874861808 100644
--- a/dev/Interop/StoragePickers/PickerCommon.cpp
+++ b/dev/Interop/StoragePickers/PickerCommon.cpp
@@ -357,10 +357,10 @@ namespace PickerCommon {
             FileTypeFilterPara.push_back({ FileTypeFilterData.at(i * 2).c_str(), FileTypeFilterData.at(i * 2 + 1).c_str() });
         }
 
-        if (DefaultFileTypeIndex == -1)
+        if (!DefaultFileTypeIndex.has_value())
         {
             // If the DefaultFileTypeIndex is not specified by the user, set to focuse the last one ("All Files")
-            DefaultFileTypeIndex = static_cast<int>(resultSize) - 1;
+            DefaultFileTypeIndex = static_cast<uint32_t>(resultSize - 1);
         }
     }
 
@@ -468,9 +468,9 @@ namespace PickerCommon {
         {
             check_hresult(dialog->SetFileTypes((UINT)FileTypeFilterPara.size(), FileTypeFilterPara.data()));
 
-            if (DefaultFileTypeIndex != -1 && DefaultFileTypeIndex < static_cast<int>(FileTypeFilterPara.size()))
+            if (DefaultFileTypeIndex.has_value() && *DefaultFileTypeIndex < static_cast<uint32_t>(FileTypeFilterPara.size()))
             {
-                check_hresult(dialog->SetFileTypeIndex(DefaultFileTypeIndex + 1)); // COMDLG file type index is 1-based
+                check_hresult(dialog->SetFileTypeIndex(static_cast<UINT>(*DefaultFileTypeIndex + 1))); // COMDLG file type index is 1-based
             }
         }
 
diff --git a/dev/Interop/StoragePickers/PickerCommon.h b/dev/Interop/StoragePickers/PickerCommon.h
index a112323a69..a682017af2 100644
--- a/dev/Interop/StoragePickers/PickerCommon.h
+++ b/dev/Interop/StoragePickers/PickerCommon.h
@@ -8,6 +8,7 @@
 #include <winrt/Windows.Security.Cryptography.h>
 #include <winrt/Windows.Security.Cryptography.Core.h>
 #include <winrt/Microsoft.UI.Windowing.h>
+#include <optional>
 
 namespace PickerCommon {
     winrt::hstring GetPathFromShellItem(winrt::com_ptr<IShellItem> shellItem);
@@ -36,7 +37,7 @@ namespace PickerCommon {
         winrt::Microsoft::Windows::Storage::Pickers::PickerLocationId SuggestedStartLocation;
         std::vector<winrt::hstring> FileTypeFilterData{};
         std::vector<COMDLG_FILTERSPEC> FileTypeFilterPara{};
-        int DefaultFileTypeIndex{ -1 };
+        std::optional<uint32_t> DefaultFileTypeIndex{};
         winrt::hstring AllFilesText{ L"All Files" }; // initialize to All Files as a default value, will be updated by localization
 
         winrt::hstring SuggestedFileName;