Manually dismiss popups when the window moves, or the SUI scrolls (#10922)

## Summary of the Pull Request

BODGY!

This solution was suggested in https://github.com/microsoft/microsoft-ui-xaml/issues/4554#issuecomment-887815332.

When the window moves, or when a ScrollViewer scrolls, dismiss any popups that are visible. This happens automagically when an app is a real XAML app, but it doesn't work for XAML Islands.

## References
* upstream at https://github.com/microsoft/microsoft-ui-xaml/issues/4554

## PR Checklist
* [x] Closes #9320
* [x] I work here
* [ ] Tests added/passed
* [ ] Requires documentation to be updated

## Detailed Description of the Pull Request / Additional comments

Unfortunately, we've got a bunch of scroll viewers in our SUI. So I did something bodgyx2 to make our life a little easier.

`DismissAllPopups` can be used to dismiss all popups for a particular UI element. However, we've got a bunch of pages with scroll viewers that may or may not have popups in them. Rather than define the same exact body for all their `ViewChanging` events, the `HasScrollViewer` struct will just do it for you!

Inside the `HasScrollViewer` stuct, we can't get at the `XamlRoot()` that our subclass implements. I mean, _we_ can, but when XAML does it's codegen, _XAML_ won't be able to figure it out.

Fortunately for us, we don't need to! The sender is a UIElement, so we can just get _their_ `XamlRoot()`.

So, you can fix this for any SUI page with just a simple 

```diff
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
```

```diff
-    struct AddProfile : AddProfileT<AddProfile>
+    struct AddProfile : public HasScrollViewer<AddProfile>, AddProfileT<AddProfile>
```

## Validation Steps Performed

* the window doesn't close when you move it
* the popups _do_ close when you move the window
* the popups close when you scroll any SUI page

src/cascadia/TerminalSettingsEditor/Actions.h

@@ -107,7 +107,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(Model::CascadiaSettings, Settings, nullptr)
     };
 
-    struct Actions : ActionsT<Actions>
+    struct Actions : public HasScrollViewer<Actions>, ActionsT<Actions>
     {
     public:
         Actions();

src/cascadia/TerminalSettingsEditor/Actions.xaml

@@ -374,7 +374,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel MaxWidth="600"
                     Spacing="8"
                     Style="{StaticResource SettingsStackStyle}">

src/cascadia/TerminalSettingsEditor/AddProfile.h

@@ -43,7 +43,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_CALLBACK(AddNew, AddNewArgs);
     };
 
-    struct AddProfile : AddProfileT<AddProfile>
+    struct AddProfile : public HasScrollViewer<AddProfile>, AddProfileT<AddProfile>
     {
     public:
         AddProfile();

src/cascadia/TerminalSettingsEditor/AddProfile.xaml

@@ -21,7 +21,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Style="{StaticResource SettingsStackStyle}">
             <Button x:Uid="AddProfile_AddNewButton"
                     AutomationProperties.AutomationId="AddProfile_AddNewButton"

src/cascadia/TerminalSettingsEditor/ColorSchemes.h

@@ -20,7 +20,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(winrt::hstring, LastSelectedScheme, L"");
     };
 
-    struct ColorSchemes : ColorSchemesT<ColorSchemes>
+    struct ColorSchemes : public HasScrollViewer<ColorSchemes>, ColorSchemesT<ColorSchemes>
     {
         ColorSchemes();
 

src/cascadia/TerminalSettingsEditor/ColorSchemes.xaml

@@ -93,7 +93,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Margin="{StaticResource StandardIndentMargin}"
                     Spacing="24">
 

src/cascadia/TerminalSettingsEditor/GlobalAppearance.h

@@ -18,7 +18,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(Model::GlobalAppSettings, Globals, nullptr)
     };
 
-    struct GlobalAppearance : GlobalAppearanceT<GlobalAppearance>
+    struct GlobalAppearance : public HasScrollViewer<GlobalAppearance>, GlobalAppearanceT<GlobalAppearance>
     {
     public:
         GlobalAppearance();

src/cascadia/TerminalSettingsEditor/GlobalAppearance.xaml

@@ -24,7 +24,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Style="{StaticResource SettingsStackStyle}">
             <!--  Language  -->
             <local:SettingContainer x:Uid="Globals_Language"

src/cascadia/TerminalSettingsEditor/Interaction.h

@@ -18,7 +18,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(Model::GlobalAppSettings, Globals, nullptr)
     };
 
-    struct Interaction : InteractionT<Interaction>
+    struct Interaction : public HasScrollViewer<Interaction>, InteractionT<Interaction>
     {
         Interaction();
 

src/cascadia/TerminalSettingsEditor/Interaction.xaml

@@ -24,7 +24,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Style="{StaticResource SettingsStackStyle}">
             <!--  Copy On Select  -->
             <local:SettingContainer x:Uid="Globals_CopyOnSelect"

src/cascadia/TerminalSettingsEditor/Launch.h

@@ -18,7 +18,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(Model::CascadiaSettings, Settings, nullptr)
     };
 
-    struct Launch : LaunchT<Launch>
+    struct Launch : public HasScrollViewer<Launch>, LaunchT<Launch>
     {
     public:
         Launch();

src/cascadia/TerminalSettingsEditor/Launch.xaml

@@ -33,7 +33,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel>
             <StackPanel Style="{StaticResource SettingsStackStyle}">
                 <!--  Default Profile  -->

src/cascadia/TerminalSettingsEditor/Profiles.h

@@ -153,7 +153,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         Windows::Foundation::Collections::IMapView<hstring, Model::ColorScheme> _Schemes;
     };
 
-    struct Profiles : ProfilesT<Profiles>
+    struct Profiles : public HasScrollViewer<Profiles>, ProfilesT<Profiles>
     {
     public:
         Profiles();

src/cascadia/TerminalSettingsEditor/Profiles.xaml

@@ -56,7 +56,7 @@
                SelectionChanged="Pivot_SelectionChanged">
             <!--  General Tab  -->
             <PivotItem x:Uid="Profile_General">
-                <ScrollViewer>
+                <ScrollViewer ViewChanging="ViewChanging">
                     <StackPanel Style="{StaticResource PivotStackStyle}">
 
                         <!--  Name  -->
@@ -225,7 +225,7 @@
 
             <!--  Appearance Tab  -->
             <PivotItem x:Uid="Profile_Appearance">
-                <ScrollViewer>
+                <ScrollViewer ViewChanging="ViewChanging">
                     <StackPanel>
                         <!--  Control Preview  -->
                         <Border x:Name="ControlPreview"
@@ -397,7 +397,7 @@
 
             <!--  Advanced Tab  -->
             <PivotItem x:Uid="Profile_Advanced">
-                <ScrollViewer>
+                <ScrollViewer ViewChanging="ViewChanging">
                     <StackPanel Style="{StaticResource PivotStackStyle}">
                         <!--  Suppress Application Title  -->
                         <local:SettingContainer x:Uid="Profile_SuppressApplicationTitle"

src/cascadia/TerminalSettingsEditor/ReadOnlyActions.h

@@ -32,7 +32,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         TYPED_EVENT(OpenJson, Windows::Foundation::IInspectable, Model::SettingsTarget);
     };
 
-    struct ReadOnlyActions : ReadOnlyActionsT<ReadOnlyActions>
+    struct ReadOnlyActions : public HasScrollViewer<ReadOnlyActions>, ReadOnlyActionsT<ReadOnlyActions>
     {
     public:
         ReadOnlyActions();

src/cascadia/TerminalSettingsEditor/ReadOnlyActions.xaml

@@ -182,7 +182,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Style="{StaticResource SettingsStackStyle}">
             <TextBlock x:Uid="Globals_KeybindingsDisclaimer"
                        Style="{StaticResource DisclaimerStyle}" />

src/cascadia/TerminalSettingsEditor/Rendering.h

@@ -18,7 +18,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_PROPERTY(Model::GlobalAppSettings, Globals, nullptr)
     };
 
-    struct Rendering : RenderingT<Rendering>
+    struct Rendering : public HasScrollViewer<Rendering>, RenderingT<Rendering>
     {
         Rendering();
 

src/cascadia/TerminalSettingsEditor/Rendering.xaml

@@ -18,7 +18,7 @@
         </ResourceDictionary>
     </Page.Resources>
 
-    <ScrollViewer>
+    <ScrollViewer ViewChanging="ViewChanging">
         <StackPanel Style="{StaticResource SettingsStackStyle}">
             <TextBlock x:Uid="Globals_RenderingDisclaimer"
                        Style="{StaticResource DisclaimerStyle}" />

src/cascadia/TerminalSettingsEditor/Utils.h

@@ -138,3 +138,41 @@ namespace winrt::Microsoft::Terminal::Settings
     winrt::hstring GetSelectedItemTag(winrt::Windows::Foundation::IInspectable const& comboBoxAsInspectable);
     winrt::hstring LocalizedNameForEnumName(const std::wstring_view sectionAndType, const std::wstring_view enumValue, const std::wstring_view propertyType);
 }
+
+// BODGY!
+//
+// The following function and struct are a workaround for GH#9320.
+//
+// DismissAllPopups can be used to dismiss all popups for a particular UI
+// element. However, we've got a bunch of pages with scroll viewers that may or
+// may not have popups in them. Rather than define the same exact body for all
+// their ViewChanging events, the HasScrollViewer struct will just do it for
+// you!
+inline void DismissAllPopups(winrt::Windows::UI::Xaml::XamlRoot const& xamlRoot)
+{
+    const auto popups{ winrt::Windows::UI::Xaml::Media::VisualTreeHelper::GetOpenPopupsForXamlRoot(xamlRoot) };
+    for (const auto& p : popups)
+    {
+        p.IsOpen(false);
+    }
+}
+
+template<typename T>
+struct HasScrollViewer
+{
+    // When the ScrollViewer scrolls, dismiss any popups we might have.
+    void ViewChanging(winrt::Windows::Foundation::IInspectable const& sender,
+                      const winrt::Windows::UI::Xaml::Controls::ScrollViewerViewChangingEventArgs& /*e*/)
+    {
+        // Inside this struct, we can't get at the XamlRoot() that our subclass
+        // implements. I mean, _we_ can, but when XAML does it's code
+        // generation, _XAML_ won't be able to figure it out.
+        //
+        // Fortunately for us, we don't need to! The sender is a UIElement, so
+        // we can just get _their_ XamlRoot().
+        if (const auto& uielem{ sender.try_as<winrt::Windows::UI::Xaml::UIElement>() })
+        {
+            DismissAllPopups(uielem.XamlRoot());
+        }
+    }
+};

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -79,6 +79,7 @@ AppHost::AppHost() noexcept :
                                                 std::placeholders::_2));
     _window->MouseScrolled({ this, &AppHost::_WindowMouseWheeled });
     _window->WindowActivated({ this, &AppHost::_WindowActivated });
+    _window->WindowMoved({ this, &AppHost::_WindowMoved });
     _window->HotkeyPressed({ this, &AppHost::_GlobalHotkeyPressed });
     _window->SetAlwaysOnTop(_logic.GetInitialAlwaysOnTop());
     _window->MakeWindow();
@@ -1095,3 +1096,29 @@ winrt::fire_and_forget AppHost::_HideTrayIconRequested()
         }
     }
 }
+
+// Method Description:
+// - BODGY workaround for GH#9320. When the window moves, dismiss all the popups
+//   in the UI tree. Xaml Islands unfortunately doesn't do this for us, see
+//   microsoft/microsoft-ui-xaml#4554
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+void AppHost::_WindowMoved()
+{
+    if (_logic)
+    {
+        const auto root{ _logic.GetRoot() };
+
+        // This is basically DismissAllPopups which is also in
+        // TerminalSettingsEditor/Utils.h
+        // There isn't a good place that's shared between these two files, but
+        // it's only 5 LOC so whatever.
+        const auto popups{ Media::VisualTreeHelper::GetOpenPopupsForXamlRoot(root.XamlRoot()) };
+        for (const auto& p : popups)
+        {
+            p.IsOpen(false);
+        }
+    }
+}

src/cascadia/WindowsTerminal/AppHost.h

@@ -48,6 +48,7 @@ private:
                           const winrt::Windows::Foundation::IInspectable& arg);
     void _WindowMouseWheeled(const til::point coord, const int32_t delta);
     winrt::fire_and_forget _WindowActivated();
+    void _WindowMoved();
 
     void _DispatchCommandline(winrt::Windows::Foundation::IInspectable sender,
                               winrt::Microsoft::Terminal::Remoting::CommandlineArgs args);

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -465,6 +465,11 @@ long IslandWindow::_calculateTotalSize(const bool isWidth, const long clientSize
     {
         return _OnMoving(wparam, lparam);
     }
+    case WM_MOVE:
+    {
+        _WindowMovedHandlers();
+        break;
+    }
     case WM_CLOSE:
     {
         // If the user wants to close the app by clicking 'X' button,

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -57,10 +57,13 @@ public:
     WINRT_CALLBACK(WindowActivated, winrt::delegate<void()>);
     WINRT_CALLBACK(HotkeyPressed, winrt::delegate<void(long)>);
     WINRT_CALLBACK(NotifyTrayIconPressed, winrt::delegate<void()>);
+    WINRT_CALLBACK(NotifyWindowHidden, winrt::delegate<void()>);
     WINRT_CALLBACK(NotifyShowTrayContextMenu, winrt::delegate<void(til::point)>);
     WINRT_CALLBACK(NotifyTrayMenuItemSelected, winrt::delegate<void(HMENU, UINT)>);
     WINRT_CALLBACK(NotifyReAddTrayIcon, winrt::delegate<void()>);
 
+    WINRT_CALLBACK(WindowMoved, winrt::delegate<void()>);
+
 protected:
     void ForceResize()
     {

src/cascadia/WindowsTerminal/pch.h

@@ -60,8 +60,10 @@ Abstract:
 //  * Controls for grid
 //  * Media for ScaleTransform
 //  * ApplicationModel for finding the path to wt.exe
+//  * Primitives for Popup (used by GetOpenPopupsForXamlRoot)
 #include <winrt/Windows.UI.Core.h>
 #include <winrt/Windows.UI.Xaml.Controls.h>
+#include <winrt/Windows.UI.Xaml.Controls.Primitives.h>
 #include <winrt/Windows.ui.xaml.media.h>
 #include <winrt/Windows.ApplicationModel.h>
 #include <winrt/Windows.ApplicationModel.Resources.Core.h>