Propagate the hosting HWND to the new IFileDialogs (#9789)

This is required to maintain the modality of the dialogs, which we lost
when we moved from Pickers to IFileDialog. The HWND hosting Window API
we dreamed up is incompatible with IModalDialog, because IModalDialog
requires the HWND immediately upon `Show`. We're smuggling it in a
uint64, as is tradition.

zadjii-msft noticed this in #9760.

src/cascadia/TerminalSettingsEditor/MainPage.cpp

@@ -182,6 +182,11 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         return false;
     }
 
+    uint64_t MainPage::GetHostingWindow() const noexcept
+    {
+        return reinterpret_cast<uint64_t>(_hostingHwnd.value_or(nullptr));
+    }
+
     // Function Description:
     // - Called when the NavigationView is loaded. Navigates to the first item in the NavigationView, if no item is selected
     // Arguments:

src/cascadia/TerminalSettingsEditor/MainPage.h

@@ -24,6 +24,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 
         void SetHostingWindow(uint64_t hostingWindow) noexcept;
         bool TryPropagateHostingWindow(IInspectable object) noexcept;
+        uint64_t GetHostingWindow() const noexcept;
 
         TYPED_EVENT(OpenJson, Windows::Foundation::IInspectable, Model::SettingsTarget);
 

src/cascadia/TerminalSettingsEditor/MainPage.idl

@@ -10,6 +10,7 @@ namespace Microsoft.Terminal.Settings.Editor
     interface IHostedInWindow
     {
         Boolean TryPropagateHostingWindow(IInspectable i);
+        UInt64 GetHostingWindow();
     }
 
     [default_interface] runtimeclass MainPage : Windows.UI.Xaml.Controls.Page, IHostedInWindow

src/cascadia/TerminalSettingsEditor/Profiles.cpp

@@ -29,15 +29,15 @@ static const std::array<winrt::guid, 2> InBoxProfileGuids{
 // Return value:
 // (async) path to the selected item.
 template<typename TLambda>
-static winrt::Windows::Foundation::IAsyncOperation<winrt::hstring> OpenFilePicker(TLambda&& customize)
+static winrt::Windows::Foundation::IAsyncOperation<winrt::hstring> OpenFilePicker(HWND parentHwnd, TLambda&& customize)
 {
     auto fileDialog{ winrt::create_instance<IFileDialog>(CLSID_FileOpenDialog) };
     DWORD flags{};
     THROW_IF_FAILED(fileDialog->GetOptions(&flags));
     THROW_IF_FAILED(fileDialog->SetOptions(flags | FOS_FORCEFILESYSTEM | FOS_NOCHANGEDIR | FOS_DONTADDTORECENT)); // filesystem objects only; no recent places
     customize(fileDialog.get());
 
-    auto hr{ fileDialog->Show(NULL) };
+    auto hr{ fileDialog->Show(parentHwnd) };
     if (!SUCCEEDED(hr))
     {
         if (hr == HRESULT_FROM_WIN32(ERROR_CANCELLED))
@@ -58,15 +58,15 @@ static winrt::Windows::Foundation::IAsyncOperation<winrt::hstring> OpenFilePicke
 
 // Function Description:
 // - Helper that opens a file picker pre-seeded with image file types.
-static winrt::Windows::Foundation::IAsyncOperation<winrt::hstring> OpenImagePicker()
+static winrt::Windows::Foundation::IAsyncOperation<winrt::hstring> OpenImagePicker(HWND parentHwnd)
 {
     static constexpr COMDLG_FILTERSPEC supportedImageFileTypes[] = {
         { L"All Supported Bitmap Types (*.jpg, *.jpeg, *.png, *.bmp, *.gif, *.tiff, *.ico)", L"*.jpg;*.jpeg;*.png;*.bmp;*.gif;*.tiff;*.ico" },
         { L"All Files (*.*)", L"*.*" }
     };
 
     static constexpr winrt::guid clientGuidImagePicker{ 0x55675F54, 0x74A1, 0x4552, { 0xA3, 0x9D, 0x94, 0xAE, 0x85, 0xD8, 0xF2, 0x7A } };
-    return OpenFilePicker([](auto&& dialog) {
+    return OpenFilePicker(parentHwnd, [](auto&& dialog) {
         THROW_IF_FAILED(dialog->SetClientGuid(clientGuidImagePicker));
         try
         {
@@ -637,7 +637,8 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
     {
         auto lifetime = get_strong();
 
-        auto file = co_await OpenImagePicker();
+        const auto parentHwnd{ reinterpret_cast<HWND>(_State.WindowRoot().GetHostingWindow()) };
+        auto file = co_await OpenImagePicker(parentHwnd);
         if (!file.empty())
         {
             _State.Profile().BackgroundImagePath(file);
@@ -648,7 +649,8 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
     {
         auto lifetime = get_strong();
 
-        auto file = co_await OpenImagePicker();
+        const auto parentHwnd{ reinterpret_cast<HWND>(_State.WindowRoot().GetHostingWindow()) };
+        auto file = co_await OpenImagePicker(parentHwnd);
         if (!file.empty())
         {
             _State.Profile().Icon(file);
@@ -665,7 +667,8 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         };
 
         static constexpr winrt::guid clientGuidExecutables{ 0x2E7E4331, 0x0800, 0x48E6, { 0xB0, 0x17, 0xA1, 0x4C, 0xD8, 0x73, 0xDD, 0x58 } };
-        auto path = co_await OpenFilePicker([](auto&& dialog) {
+        const auto parentHwnd{ reinterpret_cast<HWND>(_State.WindowRoot().GetHostingWindow()) };
+        auto path = co_await OpenFilePicker(parentHwnd, [](auto&& dialog) {
             THROW_IF_FAILED(dialog->SetClientGuid(clientGuidExecutables));
             try
             {
@@ -687,7 +690,8 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
     fire_and_forget Profiles::StartingDirectory_Click(IInspectable const&, RoutedEventArgs const&)
     {
         auto lifetime = get_strong();
-        auto folder = co_await OpenFilePicker([](auto&& dialog) {
+        const auto parentHwnd{ reinterpret_cast<HWND>(_State.WindowRoot().GetHostingWindow()) };
+        auto folder = co_await OpenFilePicker(parentHwnd, [](auto&& dialog) {
             static constexpr winrt::guid clientGuidFolderPicker{ 0xAADAA433, 0xB04D, 0x4BAE, { 0xB1, 0xEA, 0x1E, 0x6C, 0xD1, 0xCD, 0xA6, 0x8B } };
             THROW_IF_FAILED(dialog->SetClientGuid(clientGuidFolderPicker));
             try