Implement custom text context menus to fix crashes (#18854)

This works around a bug in WinUI where it creates a single context
menu/flyout for text elements per thread, not per `XamlRoot`, similar to
many other areas. Since the `XamlRoot` cannot change after creation,
this means that once you've opened the flyout, you're locked into that
window (= XAML root) forever. You can't open the flyout in another
window and once you've closed that window, you can't open it anywhere at
all.

Closes #18599

## Validation Steps Performed
* Flies out right click in the
  * About dialog ✅
  * Search dialog ✅
  * Word delimiters setting ✅
  * Launch size setting ✅
* Across two windows ✅

.github/actions/spelling/expect/expect.txt

@@ -128,6 +128,7 @@ Blt
 blu
 BLUESCROLL
 bmi
+bodgy
 BODGY
 BOLDFONT
 Borland
@@ -371,8 +372,8 @@ Dcd
 DColor
 dcommon
 DComposition
-dde
 DDDCCC
+dde
 DDESHARE
 DDevice
 DEADCHAR

src/cascadia/TerminalApp/AboutDialog.xaml

@@ -8,6 +8,7 @@
                xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                xmlns:local="using:TerminalApp"
                xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+               xmlns:mtu="using:Microsoft.Terminal.UI"
                xmlns:mux="using:Microsoft.UI.Xaml.Controls"
                x:Uid="AboutDialog"
                DefaultButton="Close"
@@ -17,6 +18,9 @@
 
     <StackPanel Orientation="Vertical">
         <TextBlock IsTextSelectionEnabled="True">
+            <TextBlock.ContextFlyout>
+                <mtu:TextMenuFlyout />
+            </TextBlock.ContextFlyout>
             <Run AutomationProperties.HeadingLevel="1"
                  Text="{x:Bind ApplicationDisplayName}" /> <LineBreak />
             <Run x:Uid="AboutDialog_VersionLabel" />
@@ -39,7 +43,7 @@
                         VerticalAlignment="Center"
                         Orientation="Vertical"
                         Visibility="{x:Bind UpdatesAvailable, Mode=OneWay}">
-                <TextBlock IsTextSelectionEnabled="False">
+                <TextBlock>
                     <Run x:Uid="AboutDialog_UpdateAvailableLabel" />
                 </TextBlock>
                 <!-- <Button x:Uid="AboutDialog_InstallUpdateButton"
@@ -59,4 +63,3 @@
                          Click="_ThirdPartyNoticesOnClick" />
     </StackPanel>
 </ContentDialog>
-

src/cascadia/TerminalApp/CommandPalette.xaml

@@ -284,7 +284,11 @@
                      IsSpellCheckEnabled="False"
                      PlaceholderText="{x:Bind SearchBoxPlaceholderText, Mode=OneWay}"
                      Text=""
-                     TextChanged="_filterTextChanged" />
+                     TextChanged="_filterTextChanged">
+                <TextBox.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBox.ContextFlyout>
+            </TextBox>
 
             <TextBlock x:Name="_prefixCharacter"
                        Grid.Row="0"

src/cascadia/TerminalApp/MarkdownPaneContent.cpp

@@ -78,6 +78,7 @@ namespace winrt::TerminalApp::implementation
     void MarkdownPaneContent::_loadText()
     {
         auto block = WUX::Controls::TextBlock();
+        block.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
         block.IsTextSelectionEnabled(true);
         block.FontFamily(WUX::Media::FontFamily{ L"Cascadia Code" });
         block.Text(FileContents());

src/cascadia/TerminalApp/MarkdownPaneContent.xaml

@@ -8,6 +8,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="using:TerminalApp"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:mtu="using:Microsoft.Terminal.UI"
              xmlns:mux="using:Microsoft.UI.Xaml.Controls"
              mc:Ignorable="d">
 
@@ -51,7 +52,11 @@
                      Grid.Column="0"
                      Margin="4"
                      PlaceholderText="Enter a path to a markdown file..."
-                     Text="Z:\dev\simple-test.md" />
+                     Text="Z:\dev\simple-test.md">
+                <TextBox.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBox.ContextFlyout>
+            </TextBox>
             <StackPanel Grid.Column="1"
                         Orientation="Horizontal">
                 <Button Margin="4"
@@ -105,7 +110,11 @@
                      FontFamily="Cascadia Code"
                      IsSpellCheckEnabled="False"
                      Text="{x:Bind FileContents, Mode=TwoWay}"
-                     Visibility="{x:Bind Editing}" />
+                     Visibility="{x:Bind Editing}">
+                <TextBox.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBox.ContextFlyout>
+            </TextBox>
 
             <ScrollViewer x:Name="_scrollViewer"
                           Grid.Column="1"

src/cascadia/TerminalApp/ScratchpadContent.cpp

@@ -20,6 +20,7 @@ namespace winrt::TerminalApp::implementation
         _root.Background(bg.try_as<Media::Brush>());
 
         _box = winrt::Windows::UI::Xaml::Controls::TextBox{};
+        _box.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
         _box.Margin({ 10, 10, 10, 10 });
         _box.AcceptsReturn(true);
         _box.TextWrapping(TextWrapping::Wrap);

src/cascadia/TerminalApp/SnippetsPaneContent.xaml

@@ -182,7 +182,6 @@
                                    Grid.Column="1"
                                    Margin="12,0,12,6"
                                    FontFamily="Cascadia Mono, Consolas"
-                                   IsTextSelectionEnabled="False"
                                    Style="{ThemeResource BodyTextBlockStyle}"
                                    Text="{x:Bind Input}"
                                    Visibility="{Binding ElementName=rootItem, Path=IsSelected}" />
@@ -263,7 +262,11 @@
                  Margin="8,0,8,8"
                  AllowFocusOnInteraction="True"
                  TextChanged="_filterTextChanged"
-                 Visibility="{x:Bind HasSnippets, Mode=OneWay}" />
+                 Visibility="{x:Bind HasSnippets, Mode=OneWay}">
+            <TextBox.ContextFlyout>
+                <mtu:TextMenuFlyout />
+            </TextBox.ContextFlyout>
+        </TextBox>
 
         <mux:TreeView x:Name="_treeView"
                       Grid.Row="2"

src/cascadia/TerminalApp/SuggestionsControl.xaml

@@ -141,7 +141,11 @@
                      PlaceholderText="{x:Bind SearchBoxPlaceholderText, Mode=OneWay}"
                      Text=""
                      TextChanged="_filterTextChanged"
-                     Visibility="Collapsed" />
+                     Visibility="Collapsed">
+                <TextBox.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBox.ContextFlyout>
+            </TextBox>
 
             <StackPanel Grid.Row="1"
                         Margin="8,0,8,8"
@@ -224,7 +228,11 @@
                            FontSize="14"
                            FontWeight="Bold"
                            IsTextSelectionEnabled="True"
-                           TextWrapping="WrapWholeWords" />
+                           TextWrapping="WrapWholeWords">
+                    <TextBlock.ContextFlyout>
+                        <mtu:TextMenuFlyout />
+                    </TextBlock.ContextFlyout>
+                </TextBlock>
                 <ScrollViewer MaxHeight="64"
                               VerticalScrollBarVisibility="Visible"
                               VerticalScrollMode="Enabled"
@@ -232,7 +240,11 @@
                     <TextBlock x:Name="_descriptionComment"
                                Margin="0,0,20,0"
                                IsTextSelectionEnabled="True"
-                               TextWrapping="WrapWholeWords" />
+                               TextWrapping="WrapWholeWords">
+                        <TextBlock.ContextFlyout>
+                            <mtu:TextMenuFlyout />
+                        </TextBlock.ContextFlyout>
+                    </TextBlock>
                 </ScrollViewer>
             </StackPanel>
 

src/cascadia/TerminalApp/TabHeaderControl.xaml

@@ -9,6 +9,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="using:TerminalApp"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:mtu="using:Microsoft.Terminal.UI"
              xmlns:mux="using:Microsoft.UI.Xaml.Controls"
              MinHeight="16"
              mc:Ignorable="d">
@@ -67,6 +68,10 @@
                  IsSpellCheckEnabled="False"
                  LostFocus="RenameBoxLostFocusHandler"
                  MaxLength="1024"
-                 Visibility="Collapsed" />
+                 Visibility="Collapsed">
+            <TextBox.ContextFlyout>
+                <mtu:TextMenuFlyout />
+            </TextBox.ContextFlyout>
+        </TextBox>
     </StackPanel>
 </UserControl>

src/cascadia/TerminalApp/TabRowControl.xaml

@@ -70,8 +70,7 @@
                                  FontSize="12">
                     <ToolTipService.ToolTip>
                         <ToolTip Placement="Mouse">
-                            <TextBlock IsTextSelectionEnabled="False"
+                            <TextBlock TextWrapping="Wrap">
-                                       TextWrapping="Wrap">
                                 <Run x:Uid="NewTabRun" /> <LineBreak />
                                 <Run x:Uid="NewPaneRun"
                                      FontStyle="Italic" /> <LineBreak />

src/cascadia/TerminalApp/TerminalPage.xaml

@@ -137,6 +137,9 @@
                        DefaultButton="Primary">
             <TextBlock IsTextSelectionEnabled="True"
                        TextWrapping="WrapWholeWords">
+                <TextBlock.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBlock.ContextFlyout>
                 <Run x:Name="NoticeMessage" />
             </TextBlock>
         </ContentDialog>
@@ -148,6 +151,9 @@
                        DefaultButton="Primary">
             <TextBlock IsTextSelectionEnabled="True"
                        TextWrapping="WrapWholeWords">
+                <TextBlock.ContextFlyout>
+                    <mtu:TextMenuFlyout />
+                </TextBlock.ContextFlyout>
                 <Run x:Name="CouldNotOpenUriReason" /> <LineBreak />
                 <Run x:Name="UnopenedUri"
                      FontFamily="Cascadia Mono" />
@@ -191,7 +197,11 @@
                 <TextBox x:Name="WindowRenamerTextBox"
                          KeyDown="_WindowRenamerKeyDown"
                          KeyUp="_WindowRenamerKeyUp"
-                         Text="{x:Bind WindowProperties.WindowName, Mode=OneWay}" />
+                         Text="{x:Bind WindowProperties.WindowName, Mode=OneWay}">
+                    <TextBox.ContextFlyout>
+                        <mtu:TextMenuFlyout />
+                    </TextBox.ContextFlyout>
+                </TextBox>
             </mux:TeachingTip.Content>
         </mux:TeachingTip>
 

src/cascadia/TerminalApp/TerminalWindow.cpp

@@ -434,6 +434,7 @@ namespace winrt::TerminalApp::implementation
         auto buttonText = RS_(L"Ok");
 
         Controls::TextBlock warningsTextBlock;
+        warningsTextBlock.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
         // Make sure you can copy-paste
         warningsTextBlock.IsTextSelectionEnabled(true);
         // Make sure the lines of text wrap
@@ -483,6 +484,7 @@ namespace winrt::TerminalApp::implementation
         auto buttonText = RS_(L"Ok");
 
         Controls::TextBlock warningsTextBlock;
+        warningsTextBlock.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
         // Make sure you can copy-paste
         warningsTextBlock.IsTextSelectionEnabled(true);
         // Make sure the lines of text wrap

src/cascadia/TerminalControl/SearchBoxControl.xaml

@@ -4,6 +4,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="using:Microsoft.Terminal.Control"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:mtu="using:Microsoft.Terminal.UI"
              x:Name="Root"
              HorizontalAlignment="Stretch"
              VerticalAlignment="Top"
@@ -197,7 +198,11 @@
                  VerticalAlignment="Center"
                  IsSpellCheckEnabled="False"
                  KeyDown="TextBoxKeyDown"
-                 TextChanged="TextBoxTextChanged" />
+                 TextChanged="TextBoxTextChanged">
+            <TextBox.ContextFlyout>
+                <mtu:TextMenuFlyout />
+            </TextBox.ContextFlyout>
+        </TextBox>
 
         <TextBlock x:Name="StatusBox"
                    x:Uid="SearchBox_StatusBox"

src/cascadia/TerminalControl/TermControl.xaml

@@ -10,6 +10,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="using:Microsoft.Terminal.Control"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:mtu="using:Microsoft.Terminal.UI"
              xmlns:mux="using:Microsoft.UI.Xaml.Controls"
              HorizontalAlignment="Stretch"
              VerticalAlignment="Stretch"
@@ -1272,6 +1273,9 @@
                                          Placement="Mouse">
                                     <TextBlock IsTextSelectionEnabled="True"
                                                TextWrapping="Wrap">
+                                        <TextBlock.ContextFlyout>
+                                            <mtu:TextMenuFlyout />
+                                        </TextBlock.ContextFlyout>
                                         <Run x:Name="HoveredUri" /> <LineBreak />
                                         <Run x:Uid="HowToOpenRun"
                                              FontStyle="Italic" />

src/cascadia/TerminalSettingsEditor/CommonResources.xaml

@@ -132,6 +132,11 @@
     <Style x:Key="TextBoxSettingStyle"
            BasedOn="{StaticResource DefaultTextBoxStyle}"
            TargetType="TextBox">
+        <Setter Property="ContextFlyout">
+            <Setter.Value>
+                <mtu:TextMenuFlyout />
+            </Setter.Value>
+        </Setter>
         <Setter Property="MinWidth" Value="{StaticResource StandardBoxMinWidth}" />
         <Setter Property="MaxWidth" Value="400" />
         <Setter Property="HorizontalAlignment" Value="Left" />

src/cascadia/UIHelpers/Resources/en-US/Resources.resw

@@ -0,0 +1,136 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="Cut" xml:space="preserve">
+    <value>Cut</value>
+    <comment>"Cut" as contained in a Cut/Copy/Paste menu</comment>
+  </data>
+  <data name="Copy" xml:space="preserve">
+    <value>Copy</value>
+    <comment>"Copy" as contained in a Cut/Copy/Paste menu</comment>
+  </data>
+  <data name="Paste" xml:space="preserve">
+    <value>Paste</value>
+    <comment>"Paste" as contained in a Cut/Copy/Paste menu</comment>
+  </data>
+  <data name="SelectAll" xml:space="preserve">
+    <value>Select All</value>
+    <comment>"Select All" as contained in a Cut/Copy/Paste menu</comment>
+  </data>
+</root>

src/cascadia/UIHelpers/TextMenuFlyout.cpp

@@ -0,0 +1,204 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+#include "pch.h"
+#include "TextMenuFlyout.h"
+
+#include <LibraryResources.h>
+
+#include "TextMenuFlyout.g.cpp"
+
+using namespace ::winrt::Windows::UI::Xaml;
+using namespace ::winrt::Windows::UI::Xaml::Controls;
+using namespace ::winrt::Windows::ApplicationModel::Resources::Core;
+using namespace ::winrt::Microsoft::UI::Xaml::Controls;
+using namespace ::winrt::Windows::System;
+using namespace ::winrt::Windows::UI::Xaml::Input;
+
+using MenuFlyoutItemClick = void (*)(IInspectable const&, RoutedEventArgs const&);
+
+constexpr auto NullSymbol = static_cast<Symbol>(0);
+
+namespace winrt::Microsoft::Terminal::UI::implementation
+{
+#pragma warning(suppress : 26455) // Default constructor should not throw. Declare it 'noexcept' (f.6).
+    TextMenuFlyout::TextMenuFlyout()
+    {
+        // Most of the initialization is delayed until the first call to MenuFlyout_Opening.
+        Opening({ this, &TextMenuFlyout::MenuFlyout_Opening });
+    }
+
+    void TextMenuFlyout::MenuFlyout_Opening(IInspectable const&, IInspectable const&)
+    {
+        auto target = Target();
+        if (!target)
+        {
+            return;
+        }
+        hstring selection;
+        bool writable = false;
+
+        // > Common group of selectable controls with common actions
+        // > The I in MIDL stands for...
+        // No common interface.
+        if (const auto box = target.try_as<NumberBox>())
+        {
+            target = box.GetTemplateChild(L"InputBox").as<TextBox>();
+        }
+        if (const auto control = target.try_as<TextBlock>())
+        {
+            selection = control.SelectedText();
+        }
+        else if (const auto control = target.try_as<TextBox>())
+        {
+            selection = control.SelectedText();
+            writable = true;
+        }
+        else if (const auto control = target.try_as<RichTextBlock>())
+        {
+            selection = control.SelectedText();
+        }
+
+        if (!_copy)
+        {
+            til::small_vector<MenuFlyoutItemBase, 4> items;
+
+            if (writable)
+            {
+                _cut = items.emplace_back(_createMenuItem(Symbol::Cut, RS_(L"Cut"), { this, &TextMenuFlyout::Cut_Click }, VirtualKeyModifiers::Control, VirtualKey::X));
+            }
+            _copy = items.emplace_back(_createMenuItem(Symbol::Copy, RS_(L"Copy"), { this, &TextMenuFlyout::Copy_Click }, VirtualKeyModifiers::Control, VirtualKey::C));
+            if (writable)
+            {
+                items.emplace_back(_createMenuItem(Symbol::Paste, RS_(L"Paste"), { this, &TextMenuFlyout::Paste_Click }, VirtualKeyModifiers::Control, VirtualKey::V));
+            }
+            items.emplace_back(_createMenuItem(NullSymbol, RS_(L"SelectAll"), { this, &TextMenuFlyout::SelectAll_Click }, VirtualKeyModifiers::Control, VirtualKey::A));
+
+            Items().ReplaceAll({ items.data(), gsl::narrow_cast<uint32_t>(items.size()) });
+        }
+
+        const auto visibilityOfItemsRequiringSelection = selection.empty() ? Visibility::Collapsed : Visibility::Visible;
+        if (_cut)
+        {
+            _cut.Visibility(visibilityOfItemsRequiringSelection);
+        }
+        _copy.Visibility(visibilityOfItemsRequiringSelection);
+    }
+
+    void TextMenuFlyout::Cut_Click(IInspectable const&, RoutedEventArgs const&)
+    {
+        // NOTE: When the flyout closes, WinUI doesn't disconnect the accelerator keys.
+        // Since that means we'll get Ctrl+X/C/V callbacks forever, just ignore them.
+        // The TextBox will still handle those events...
+        auto target = Target();
+        if (!target)
+        {
+            return;
+        }
+
+        if (const auto box = target.try_as<NumberBox>())
+        {
+            target = box.GetTemplateChild(L"InputBox").as<TextBox>();
+        }
+        if (const auto control = target.try_as<TextBox>())
+        {
+            control.CutSelectionToClipboard();
+        }
+    }
+
+    void TextMenuFlyout::Copy_Click(IInspectable const&, RoutedEventArgs const&)
+    {
+        auto target = Target();
+        if (!target)
+        {
+            return;
+        }
+
+        if (const auto box = target.try_as<NumberBox>())
+        {
+            target = box.GetTemplateChild(L"InputBox").as<TextBox>();
+        }
+        if (const auto control = target.try_as<TextBlock>())
+        {
+            control.CopySelectionToClipboard();
+        }
+        else if (const auto control = target.try_as<TextBox>())
+        {
+            control.CopySelectionToClipboard();
+        }
+        else if (const auto control = target.try_as<RichTextBlock>())
+        {
+            control.CopySelectionToClipboard();
+        }
+    }
+
+    void TextMenuFlyout::Paste_Click(IInspectable const&, RoutedEventArgs const&)
+    {
+        auto target = Target();
+        if (!target)
+        {
+            return;
+        }
+
+        if (const auto box = target.try_as<NumberBox>())
+        {
+            target = box.GetTemplateChild(L"InputBox").as<TextBox>();
+        }
+        if (const auto control = target.try_as<TextBox>())
+        {
+            control.PasteFromClipboard();
+        }
+    }
+
+    void TextMenuFlyout::SelectAll_Click(IInspectable const&, RoutedEventArgs const&)
+    {
+        // BODGY:
+        // Once the flyout was open once, we'll get Ctrl+A events and the TextBox will
+        // ignore them. As such, we have to dig out the focused element as a fallback,
+        // because otherwise Ctrl+A will be permanently broken. Put differently,
+        // this is bodgy because WinUI 2.8 is buggy. There's no other solution here.
+        IInspectable target = Target();
+        if (!target)
+        {
+            target = FocusManager::GetFocusedElement(XamlRoot());
+            if (!target)
+            {
+                return;
+            }
+        }
+
+        if (const auto box = target.try_as<NumberBox>())
+        {
+            target = box.GetTemplateChild(L"InputBox").as<TextBox>();
+        }
+        if (const auto control = target.try_as<TextBlock>())
+        {
+            control.SelectAll();
+        }
+        else if (const auto control = target.try_as<TextBox>())
+        {
+            control.SelectAll();
+        }
+        else if (const auto control = target.try_as<RichTextBlock>())
+        {
+            control.SelectAll();
+        }
+    }
+
+    MenuFlyoutItemBase TextMenuFlyout::_createMenuItem(Symbol symbol, hstring text, RoutedEventHandler click, VirtualKeyModifiers modifiers, VirtualKey key)
+    {
+        KeyboardAccelerator accel;
+        accel.Modifiers(modifiers);
+        accel.Key(key);
+
+        MenuFlyoutItem item;
+        if (symbol != NullSymbol)
+        {
+            item.Icon(SymbolIcon{ std::move(symbol) });
+        }
+        item.Text(std::move(text));
+        item.Click(std::move(click));
+        item.KeyboardAccelerators().Append(std::move(accel));
+        return item;
+    }
+}

src/cascadia/UIHelpers/TextMenuFlyout.h

@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+#pragma once
+
+#include "TextMenuFlyout.g.h"
+
+namespace winrt::Microsoft::Terminal::UI::implementation
+{
+    // This custom flyout exists because WinUI 2 only supports 1 text block flyout
+    // *per thread* not per window. If you have >1 window per 1 thread, as we do,
+    // the focus will just be delegated to the window the flyout was first opened in.
+    // Once the first window is gone, WinUI will either do nothing or crash.
+    // See: GH#18599
+    struct TextMenuFlyout : TextMenuFlyoutT<TextMenuFlyout>
+    {
+        TextMenuFlyout();
+
+        void MenuFlyout_Opening(winrt::Windows::Foundation::IInspectable const& sender, winrt::Windows::Foundation::IInspectable const& e);
+        void Cut_Click(winrt::Windows::Foundation::IInspectable const& sender, winrt::Windows::UI::Xaml::RoutedEventArgs const& e);
+        void Copy_Click(winrt::Windows::Foundation::IInspectable const& sender, winrt::Windows::UI::Xaml::RoutedEventArgs const& e);
+        void Paste_Click(winrt::Windows::Foundation::IInspectable const& sender, winrt::Windows::UI::Xaml::RoutedEventArgs const& e);
+        void SelectAll_Click(winrt::Windows::Foundation::IInspectable const& sender, winrt::Windows::UI::Xaml::RoutedEventArgs const& e);
+
+    private:
+        winrt::Windows::UI::Xaml::Controls::MenuFlyoutItemBase _createMenuItem(
+            winrt::Windows::UI::Xaml::Controls::Symbol symbol,
+            winrt::hstring text,
+            winrt::Windows::UI::Xaml::RoutedEventHandler click,
+            winrt::Windows::System::VirtualKeyModifiers modifiers,
+            winrt::Windows::System::VirtualKey key);
+
+        // These are always present.
+        winrt::Windows::UI::Xaml::Controls::MenuFlyoutItemBase _copy{ nullptr };
+        // These are only set for writable controls.
+        winrt::Windows::UI::Xaml::Controls::MenuFlyoutItemBase _cut{ nullptr };
+    };
+}
+
+namespace winrt::Microsoft::Terminal::UI::factory_implementation
+{
+    BASIC_FACTORY(TextMenuFlyout);
+}

src/cascadia/UIHelpers/TextMenuFlyout.idl

@@ -0,0 +1,7 @@
+namespace Microsoft.Terminal.UI
+{
+    [default_interface] runtimeclass TextMenuFlyout : Windows.UI.Xaml.Controls.MenuFlyout
+    {
+        TextMenuFlyout();
+    }
+}

src/cascadia/UIHelpers/UIHelpers.vcxproj

@@ -26,6 +26,9 @@
     <ClInclude Include="ResourceString.h">
       <DependentUpon>ResourceString.idl</DependentUpon>
     </ClInclude>
+    <ClInclude Include="TextMenuFlyout.h">
+      <DependentUpon>TextMenuFlyout.idl</DependentUpon>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="init.cpp" />
@@ -41,6 +44,9 @@
     <ClCompile Include="ResourceString.cpp">
       <DependentUpon>ResourceString.idl</DependentUpon>
     </ClCompile>
+    <ClCompile Include="TextMenuFlyout.cpp">
+      <DependentUpon>TextMenuFlyout.idl</DependentUpon>
+    </ClCompile>
     <ClCompile Include="$(GeneratedFilesDir)module.g.cpp" />
   </ItemGroup>
   <ItemGroup>
@@ -48,6 +54,13 @@
     <Midl Include="IconPathConverter.idl" />
     <Midl Include="IDirectKeyListener.idl" />
     <Midl Include="ResourceString.idl" />
+    <Midl Include="TextMenuFlyout.idl" />
+  </ItemGroup>
+  <ItemGroup>
+    <PRIResource Include="Resources\en-US\Resources.resw">
+      <SubType>Designer</SubType>
+    </PRIResource>
+    <OCResourceDirectory Include="Resources" />
   </ItemGroup>
   <!-- ========================= Project References ======================== -->
   <ItemGroup>
@@ -64,15 +77,12 @@
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
   </ItemGroup>
-
   <ItemDefinitionGroup>
     <Link>
       <AdditionalDependencies>%(AdditionalDependencies);user32.lib;shell32.lib</AdditionalDependencies>
     </Link>
   </ItemDefinitionGroup>
-
   <Import Project="$(OpenConsoleDir)src\cppwinrt.build.post.props" />
-
   <!-- This -must- go after cppwinrt.build.post.props because that includes many VS-provided props including appcontainer.common.props, which stomps on what cppwinrt.targets did. -->
   <Import Project="$(OpenConsoleDir)src\common.nugetversions.targets" />
 </Project>

src/cascadia/UIHelpers/UIHelpers.vcxproj.filters

@@ -31,8 +31,18 @@
   </ItemGroup>
   <ItemGroup>
     <Midl Include="ResourceString.idl" />
+    <Midl Include="Converters.idl" />
+    <Midl Include="IconPathConverter.idl" />
+    <Midl Include="IDirectKeyListener.idl" />
+    <Midl Include="TextMenuFlyout.idl" />
   </ItemGroup>
   <ItemGroup>
     <Natvis Include="$(SolutionDir)tools\ConsoleTypes.natvis" />
+    <Natvis Include="$(MSBuildThisFileDirectory)..\..\natvis\wil.natvis" />
+  </ItemGroup>
+  <ItemGroup>
+    <PRIResource Include="Resources\en-US\Resources.resw">
+      <Filter>Resources\en-US</Filter>
+    </PRIResource>
   </ItemGroup>
 </Project>

src/cascadia/UIHelpers/init.cpp

@@ -3,6 +3,8 @@
 
 #include "pch.h"
 
+#include <LibraryResources.h>
+
 #pragma warning(suppress : 26440) // Not interested in changing the specification of DllMain to make it noexcept given it's an interface to the OS.
 BOOL WINAPI DllMain(HINSTANCE hInstDll, DWORD reason, LPVOID /*reserved*/)
 {
@@ -11,11 +13,11 @@ BOOL WINAPI DllMain(HINSTANCE hInstDll, DWORD reason, LPVOID /*reserved*/)
     case DLL_PROCESS_ATTACH:
         DisableThreadLibraryCalls(hInstDll);
         break;
-    case DLL_PROCESS_DETACH:
-        break;
     default:
         break;
     }
 
     return TRUE;
 }
+
+UTILS_DEFINE_LIBRARY_RESOURCE_SCOPE(L"Microsoft.Terminal.UI/Resources")

src/cascadia/UIHelpers/pch.h

@@ -25,16 +25,15 @@
 
 #include <wil/cppwinrt.h>
 
-#include <winrt/Windows.ApplicationModel.Resources.h>
+#include <winrt/Windows.ApplicationModel.Resources.Core.h>
-#include <winrt/Windows.Foundation.h>
+#include <winrt/Windows.Foundation.Collections.h>
 
 #include <winrt/Windows.Graphics.Imaging.h>
 #include <Windows.Graphics.Imaging.Interop.h>
 
-#include <winrt/Windows.UI.Text.h>
 #include <winrt/Windows.UI.Xaml.Controls.h>
 #include <winrt/Windows.UI.Xaml.Markup.h>
-#include <winrt/Windows.UI.Xaml.Media.h>
+#include <winrt/Windows.UI.Xaml.Input.h>
 #include <winrt/Windows.UI.Xaml.Media.Imaging.h>
 
 #include <winrt/Microsoft.UI.Xaml.Controls.h>

src/cascadia/UIMarkdown/CodeBlock.xaml

@@ -8,6 +8,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:local="using:Microsoft.Terminal.UI.Markdown"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:mtu="using:Microsoft.Terminal.UI"
              xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
              HorizontalAlignment="Stretch"
              VerticalAlignment="Stretch"
@@ -201,7 +202,11 @@
                       VerticalAlignment="Stretch">
                     <TextBlock FontFamily="Cascadia Mono, Consolas"
                                IsTextSelectionEnabled="True"
-                               Text="{x:Bind Commandlines}" />
+                               Text="{x:Bind Commandlines}">
+                        <TextBlock.ContextFlyout>
+                            <mtu:TextMenuFlyout />
+                        </TextBlock.ContextFlyout>
+                    </TextBlock>
                 </Grid>
             </ScrollViewer>
         </Border>

src/cascadia/UIMarkdown/MarkdownToXaml.cpp

@@ -72,6 +72,7 @@ WUX::Controls::RichTextBlock MarkdownToXaml::Convert(std::string_view markdownTe
 MarkdownToXaml::MarkdownToXaml(const winrt::hstring& baseUrl) :
     _baseUri{ baseUrl }
 {
+    _root.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
     _root.IsTextSelectionEnabled(true);
     _root.TextWrapping(WUX::TextWrapping::WrapWholeWords);
 }
@@ -155,6 +156,7 @@ void MarkdownToXaml::_EndParagraph() noexcept
 WUX::Controls::TextBlock MarkdownToXaml::_makeDefaultTextBlock()
 {
     WUX::Controls::TextBlock b{};
+    b.ContextFlyout(winrt::Microsoft::Terminal::UI::TextMenuFlyout{});
     b.IsTextSelectionEnabled(true);
     b.TextWrapping(WUX::TextWrapping::WrapWholeWords);
     return b;

src/cascadia/UIMarkdown/UIMarkdown.vcxproj

@@ -7,7 +7,6 @@
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <SubSystem>Console</SubSystem>
     <OpenConsoleUniversalApp>true</OpenConsoleUniversalApp>
-
     <!-- C++/WinRT sets the depth to 1 if there is a XAML file in the project
          Unfortunately for us, we need it to be 4. When the namespace merging
          depth is 1, Microsoft.Terminal.UI.Markdown becomes "Microsoft",
@@ -18,7 +17,6 @@
     -->
     <CppWinRTNamespaceMergeDepth>4</CppWinRTNamespaceMergeDepth>
     <XamlComponentResourceLocation>nested</XamlComponentResourceLocation>
-
   </PropertyGroup>
   <PropertyGroup Label="NuGet Dependencies">
     <TerminalCppWinrt>true</TerminalCppWinrt>
@@ -78,10 +76,11 @@
       <Project>{CA5CAD1A-039A-4929-BA2A-8BEB2E4106FE}</Project>
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
+    <ProjectReference Include="..\UIHelpers\UIHelpers.vcxproj">
+      <Project>{6515f03f-e56d-4db4-b23d-ac4fb80db36f}</Project>
+    </ProjectReference>
   </ItemGroup>
-
   <Import Project="$(OpenConsoleDir)src\cppwinrt.build.post.props" />
-
   <!-- This -must- go after cppwinrt.build.post.props because that includes many VS-provided props including appcontainer.common.props, which stomps on what cppwinrt.targets did. -->
   <Import Project="$(OpenConsoleDir)src\common.nugetversions.targets" />
-</Project>
+</Project>

src/cascadia/UIMarkdown/UIMarkdown.vcxproj.filters

@@ -25,14 +25,20 @@
     <ClCompile Include="pch.cpp">
       <Filter>Module</Filter>
     </ClCompile>
+    <ClCompile Include="MarkdownToXaml.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="pch.h" />
+    <ClInclude Include="MarkdownToXaml.h" />
   </ItemGroup>
   <ItemGroup>
     <Midl Include="Builder.idl" />
   </ItemGroup>
   <ItemGroup>
     <Natvis Include="$(SolutionDir)tools\ConsoleTypes.natvis" />
+    <Natvis Include="$(MSBuildThisFileDirectory)..\..\natvis\wil.natvis" />
   </ItemGroup>
-</Project>
+  <ItemGroup>
+    <Page Include="CodeBlock.xaml" />
+  </ItemGroup>
+</Project>

src/cascadia/UIMarkdown/pch.h

@@ -25,21 +25,19 @@
 
 #include <wil/cppwinrt.h>
 
-#include <winrt/Windows.Foundation.h>
 #include <winrt/Windows.Foundation.Collections.h>
 
 #include <winrt/Windows.UI.Text.h>
 #include <winrt/Windows.UI.Xaml.Controls.h>
-#include <winrt/Windows.UI.Xaml.Markup.h>
-#include <winrt/Windows.UI.Xaml.Media.h>
 #include <winrt/Windows.UI.Xaml.Media.Imaging.h>
 #include <winrt/Windows.UI.Xaml.Documents.h>
 #include <winrt/Windows.UI.Xaml.Input.h>
 
 #include <winrt/Microsoft.UI.Xaml.Controls.h>
-#include <winrt/Microsoft.UI.Xaml.Controls.Primitives.h>
 #include <winrt/Microsoft.UI.Xaml.XamlTypeInfo.h>
 
+#include <winrt/Microsoft.Terminal.UI.h>
+
 // Manually include til after we include Windows.Foundation to give it winrt superpowers
 #include "til.h"