CmdPal: Refactoring ContextMenu adding separators, IsCritical styling, and right-click context menus for list items (#40189)

Refactored ContextMenu into it's own control to allow displaying in
CommandBar and in response to right click on list items.

- Adds "critical" styling to context menu items flagged as `IsCritical`.
This will use the theme to style with correct color.
- Added `SeparatorContextItem` and modified `MoreCommands` to allow for
both `CommandContextItem`s and `SeparatorContextItem`s.
- Right clicking a list item with a context menu will open the context
menu at the position of the click and position the filter box at the top
of the context menu.


![image](https://github.com/user-attachments/assets/3bef6b04-28bb-4a17-b731-d9ed20c0566f)


![image](https://github.com/user-attachments/assets/37ed497c-6d98-4f04-8114-d9952127ca2e)


This PR covers:

- closes #38308
- closes #39211
- closes #38307
- closes #38261

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContextMenu.xaml.cs

@@ -0,0 +1,231 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Messaging;
+using CommunityToolkit.WinUI;
+using Microsoft.CmdPal.Ext.System;
+using Microsoft.CmdPal.UI.ViewModels;
+using Microsoft.CmdPal.UI.ViewModels.Messages;
+using Microsoft.CmdPal.UI.Views;
+using Microsoft.UI.Input;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Controls.Primitives;
+using Microsoft.UI.Xaml.Input;
+using Windows.System;
+using Windows.UI.Core;
+
+namespace Microsoft.CmdPal.UI.Controls;
+
+public sealed partial class ContextMenu : UserControl,
+    IRecipient<OpenContextMenuMessage>,
+    IRecipient<UpdateCommandBarMessage>,
+    IRecipient<TryCommandKeybindingMessage>
+{
+    public ContextMenuViewModel ViewModel { get; } = new();
+
+    public ContextMenu()
+    {
+        this.InitializeComponent();
+
+        // RegisterAll isn't AOT compatible
+        WeakReferenceMessenger.Default.Register<OpenContextMenuMessage>(this);
+        WeakReferenceMessenger.Default.Register<UpdateCommandBarMessage>(this);
+        WeakReferenceMessenger.Default.Register<TryCommandKeybindingMessage>(this);
+
+        if (ViewModel != null)
+        {
+            ViewModel.PropertyChanged += ViewModel_PropertyChanged;
+        }
+    }
+
+    public void Receive(OpenContextMenuMessage message)
+    {
+        UpdateUiForStackChange();
+    }
+
+    public void Receive(UpdateCommandBarMessage message)
+    {
+        UpdateUiForStackChange();
+    }
+
+    public void Receive(TryCommandKeybindingMessage msg)
+    {
+        var result = ViewModel?.CheckKeybinding(msg.Ctrl, msg.Alt, msg.Shift, msg.Win, msg.Key);
+
+        if (result == ContextKeybindingResult.Hide)
+        {
+            msg.Handled = true;
+            WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>();
+            UpdateUiForStackChange();
+        }
+        else if (result == ContextKeybindingResult.KeepOpen)
+        {
+            UpdateUiForStackChange();
+            msg.Handled = true;
+        }
+        else if (result == ContextKeybindingResult.Unhandled)
+        {
+            msg.Handled = false;
+        }
+    }
+
+    private void CommandsDropdown_ItemClick(object sender, ItemClickEventArgs e)
+    {
+        if (e.ClickedItem is CommandContextItemViewModel item)
+        {
+            if (InvokeCommand(item) == ContextKeybindingResult.Hide)
+            {
+                WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>();
+            }
+
+            UpdateUiForStackChange();
+        }
+    }
+
+    private void CommandsDropdown_KeyDown(object sender, KeyRoutedEventArgs e)
+    {
+        if (e.Handled)
+        {
+            return;
+        }
+
+        var ctrlPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Control).HasFlag(CoreVirtualKeyStates.Down);
+        var altPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Menu).HasFlag(CoreVirtualKeyStates.Down);
+        var shiftPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Shift).HasFlag(CoreVirtualKeyStates.Down);
+        var winPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.LeftWindows).HasFlag(CoreVirtualKeyStates.Down) ||
+            InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.RightWindows).HasFlag(CoreVirtualKeyStates.Down);
+
+        var result = ViewModel?.CheckKeybinding(ctrlPressed, altPressed, shiftPressed, winPressed, e.Key);
+
+        if (result == ContextKeybindingResult.Hide)
+        {
+            e.Handled = true;
+            WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>();
+            UpdateUiForStackChange();
+        }
+        else if (result == ContextKeybindingResult.KeepOpen)
+        {
+            e.Handled = true;
+        }
+        else if (result == ContextKeybindingResult.Unhandled)
+        {
+            e.Handled = false;
+        }
+    }
+
+    private void ViewModel_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
+    {
+        var prop = e.PropertyName;
+
+        if (prop == nameof(ContextMenuViewModel.FilteredItems))
+        {
+            UpdateUiForStackChange();
+        }
+    }
+
+    private void ContextFilterBox_TextChanged(object sender, TextChangedEventArgs e)
+    {
+        ViewModel?.SetSearchText(ContextFilterBox.Text);
+
+        if (CommandsDropdown.SelectedIndex == -1)
+        {
+            CommandsDropdown.SelectedIndex = 0;
+        }
+    }
+
+    private void ContextFilterBox_KeyDown(object sender, KeyRoutedEventArgs e)
+    {
+        var ctrlPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Control).HasFlag(CoreVirtualKeyStates.Down);
+        var altPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Menu).HasFlag(CoreVirtualKeyStates.Down);
+        var shiftPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Shift).HasFlag(CoreVirtualKeyStates.Down);
+        var winPressed = InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.LeftWindows).HasFlag(CoreVirtualKeyStates.Down) ||
+            InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.RightWindows).HasFlag(CoreVirtualKeyStates.Down);
+
+        if (e.Key == VirtualKey.Enter)
+        {
+            if (CommandsDropdown.SelectedItem is CommandContextItemViewModel item)
+            {
+                if (InvokeCommand(item) == ContextKeybindingResult.Hide)
+                {
+                    WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>();
+                }
+
+                UpdateUiForStackChange();
+
+                e.Handled = true;
+            }
+        }
+        else if (e.Key == VirtualKey.Escape ||
+            (e.Key == VirtualKey.Left && altPressed))
+        {
+            if (ViewModel.CanPopContextStack())
+            {
+                ViewModel.PopContextStack();
+                UpdateUiForStackChange();
+            }
+            else
+            {
+                WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>();
+                WeakReferenceMessenger.Default.Send<FocusSearchBoxMessage>();
+                UpdateUiForStackChange();
+            }
+
+            e.Handled = true;
+        }
+
+        CommandsDropdown_KeyDown(sender, e);
+    }
+
+    private void ContextFilterBox_PreviewKeyDown(object sender, KeyRoutedEventArgs e)
+    {
+        if (e.Key == VirtualKey.Up)
+        {
+            // navigate previous
+            if (CommandsDropdown.SelectedIndex > 0)
+            {
+                CommandsDropdown.SelectedIndex--;
+            }
+            else
+            {
+                CommandsDropdown.SelectedIndex = CommandsDropdown.Items.Count - 1;
+            }
+
+            e.Handled = true;
+        }
+        else if (e.Key == VirtualKey.Down)
+        {
+            // navigate next
+            if (CommandsDropdown.SelectedIndex < CommandsDropdown.Items.Count - 1)
+            {
+                CommandsDropdown.SelectedIndex++;
+            }
+            else
+            {
+                CommandsDropdown.SelectedIndex = 0;
+            }
+
+            e.Handled = true;
+        }
+    }
+
+    private void UpdateUiForStackChange()
+    {
+        ContextFilterBox.Text = string.Empty;
+        ViewModel?.SetSearchText(string.Empty);
+        CommandsDropdown.SelectedIndex = 0;
+    }
+
+    /// <summary>
+    /// Manually focuses our search box. This needs to be called after we're actually
+    /// In the UI tree - if we're in a Flyout, that's not until Opened()
+    /// </summary>
+    internal void FocusSearchBox()
+    {
+        ContextFilterBox.Focus(FocusState.Programmatic);
+    }
+
+    private ContextKeybindingResult InvokeCommand(CommandItemViewModel command) => ViewModel.InvokeCommand(command);
+}