Fixing issue with ComboBoxes in dialog host (#3451)

* Fixing issue with ComboBoxes in dialog host

This revert the fix that was done for #3249.
Need to revisit fix that was done and find an alternative.

* Only calling set focus one when dialog is opened.

Author: Keboo

MaterialDesignThemes.UITests/Samples/DialogHost/WithComboBox.xaml

@@ -0,0 +1,38 @@
+<UserControl x:Class="MaterialDesignThemes.UITests.Samples.DialogHost.WithComboBox"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:MaterialDesignThemes.UITests.Samples.DialogHost"
+             mc:Ignorable="d" 
+             d:DesignHeight="450" d:DesignWidth="800">
+
+  <materialDesign:DialogHost x:Name="SampleDialogHost"
+                             Loaded="DialogHost_Loaded">
+    <materialDesign:DialogHost.DialogContent>
+      <Grid Margin="16">
+        <Grid.RowDefinitions>
+          <RowDefinition />
+          <RowDefinition />
+          <RowDefinition />
+        </Grid.RowDefinitions>
+        <TextBlock Text="Please choose the desired targeted platform "
+             Margin="6"
+             FontSize="12" 
+             TextWrapping="Wrap"/>
+        <ComboBox
+          x:Name="TargetedPlatformComboBox"
+          Grid.Row="1"
+          Width="120"
+          materialDesign:HintAssist.HelperText="Targetted Platform"
+          Style="{StaticResource MaterialDesignFloatingHintComboBox}">
+          <ComboBoxItem Content="Item1"/>
+          <ComboBoxItem Content="Item2" x:Name="TargetItem"/>
+          <ComboBoxItem Content="Item3"/>
+        </ComboBox>
+
+      </Grid>
+    </materialDesign:DialogHost.DialogContent>
+  </materialDesign:DialogHost>
+</UserControl>

MaterialDesignThemes.UITests/Samples/DialogHost/WithComboBox.xaml.cs

@@ -0,0 +1,17 @@
+namespace MaterialDesignThemes.UITests.Samples.DialogHost;
+
+/// <summary>
+/// Interaction logic for WithComboBox.xaml
+/// </summary>
+public partial class WithComboBox : UserControl
+{
+    public WithComboBox()
+    {
+        InitializeComponent();
+    }
+
+    private void DialogHost_Loaded(object sender, RoutedEventArgs e)
+    {
+        SampleDialogHost.IsOpen = true;
+    }
+}

MaterialDesignThemes.UITests/WPF/ComboBoxes/ComboBoxTests.cs

@@ -145,7 +145,7 @@ public async Task OnEditableComboBox_ClickInTextArea_FocusesTextBox()
         var editableTextBox = await comboBox.GetElement<TextBox>("PART_EditableTextBox");
         var button = await stackPanel.GetElement<Button>("Button");
 
-        // Open the combobox initially
+        // Open the ComboBox initially
         await comboBox.LeftClick(Position.RightCenter);
         await Task.Delay(50);   // Allow a little time for the drop-down to open (and property to change)
         bool wasOpenAfterClickOnToggleButton = await comboBox.GetIsDropDownOpen();

MaterialDesignThemes.UITests/WPF/DialogHosts/DialogHostTests.cs

@@ -6,12 +6,8 @@
 
 namespace MaterialDesignThemes.UITests.WPF.DialogHosts;
 
-public class DialogHostTests : TestBase
+public class DialogHostTests(ITestOutputHelper output) : TestBase(output)
 {
-    public DialogHostTests(ITestOutputHelper output) : base(output)
-    {
-    }
-
     [Fact]
     public async Task OnOpenDialog_OverlayCoversContent()
     {
@@ -478,6 +474,32 @@ public async Task DialogHost_ChangesSelectedRailItem_DoesNotPerformRailChangeWhe
         Assert.True(await railItem1.GetIsSelected());
         Assert.False(await railItem2.GetIsSelected());
 
+        recorder.Success();
+    }
+
+    [Fact]
+    [Description("Issue 3450")]
+    public async Task DialogHost_WithComboBox_CanSelectItem()
+    {
+        await using var recorder = new TestRecorder(App);
+
+        IVisualElement dialogHost = await LoadUserControl<WithComboBox>();
+
+        var comboBox = await dialogHost.GetElement<ComboBox>("TargetedPlatformComboBox");
+        await Task.Delay(500);
+        await comboBox.LeftClick();
+        
+        var item = await Wait.For(() => comboBox.GetElement<ComboBoxItem>("TargetItem"));
+        await Task.Delay(TimeSpan.FromSeconds(1));
+        await item.LeftClick();
+
+        await Wait.For(async () =>
+        {
+            var index = await comboBox.GetSelectedIndex();
+            Assert.Equal(1, index);
+        });
+
+
         recorder.Success();
     }
 }

MaterialDesignThemes.Wpf/DialogHost.cs

@@ -287,7 +287,6 @@ public DialogHost()
     {
         Loaded += OnLoaded;
         Unloaded += OnUnloaded;
-        PreviewGotKeyboardFocus += OnPreviewGotKeyboardFocus;
 
         CommandBindings.Add(new CommandBinding(CloseDialogCommand, CloseDialogHandler, CloseDialogCanExecute));
         CommandBindings.Add(new CommandBinding(OpenDialogCommand, OpenDialogHandler));
@@ -433,8 +432,8 @@ public PlacementMode Placement
 
     public CornerRadius CornerRadius
     {
-        get { return (CornerRadius)GetValue(CornerRadiusProperty); }
-        set { SetValue(CornerRadiusProperty, value); }
+        get => (CornerRadius)GetValue(CornerRadiusProperty);
+        set => SetValue(CornerRadiusProperty, value);
     }
 
     public static readonly DependencyProperty DialogContentProperty = DependencyProperty.Register(
@@ -652,8 +651,8 @@ public bool IsRestoreFocusDisabled
     /// </summary>
     public event DialogOpenedEventHandler DialogOpened
     {
-        add { AddHandler(DialogOpenedEvent, value); }
-        remove { RemoveHandler(DialogOpenedEvent, value); }
+        add => AddHandler(DialogOpenedEvent, value);
+        remove => RemoveHandler(DialogOpenedEvent, value);
     }
 
     /// <summary>
@@ -699,8 +698,8 @@ protected void OnDialogOpened(DialogOpenedEventArgs eventArgs)
     /// </summary>
     public event DialogClosingEventHandler DialogClosing
     {
-        add { AddHandler(DialogClosingEvent, value); }
-        remove { RemoveHandler(DialogClosingEvent, value); }
+        add => AddHandler(DialogClosingEvent, value);
+        remove => RemoveHandler(DialogClosingEvent, value);
     }
 
     /// <summary>
@@ -742,8 +741,8 @@ protected void OnDialogClosing(DialogClosingEventArgs eventArgs)
     /// </summary>
     public event DialogClosedEventHandler DialogClosed
     {
-        add { AddHandler(DialogClosedEvent, value); }
-        remove { RemoveHandler(DialogClosedEvent, value); }
+        add => AddHandler(DialogClosedEvent, value);
+        remove => RemoveHandler(DialogClosedEvent, value);
     }
 
     /// <summary>
@@ -819,6 +818,11 @@ internal void InternalClose(object? parameter)
         var child = _popup?.Child ?? _popupContentControl;
         if (child is null) return null;
 
+        if (PresentationSource.FromVisual(child) is HwndSource hwndSource)
+        {
+            SetFocus(hwndSource.Handle);
+        }
+
         CommandManager.InvalidateRequerySuggested();
         var focusable = child.VisualDepthFirstTraversal().OfType<UIElement>().FirstOrDefault(ui => ui.Focusable);
         if (focusable is null) return null;
@@ -954,11 +958,7 @@ private void OnLoaded(object sender, RoutedEventArgs routedEventArgs)
 
     private void OnPreviewGotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
     {
-        if (_popup != null &&
-            PresentationSource.FromVisual(_popup.Child) is HwndSource hwndSource)
-        {
-            SetFocus(hwndSource.Handle);
-        }
+        
     }
 
     [SecurityCritical]