Floating window shows above on modal dialog.

Hello,

Floating window sometimes shows above on modal dialog.

If there is any solution, please let me know.

Our application has 2 windows.

- MainWindow : includes DockSite

- SubWindow : has button which show toolwindow.

Procedure is the following.

0. Show toolwindow 

1. Float the toolwindow.

2. Close toolwindow.

3. Show SubWindow.

4. Press button (Show toolwindow)

--> ToolWindow will be shown above on SubWindow.

MainWindow.xaml

<Window
    x:Class="DockingWindowSample.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="MainWindow"
    Width="800"
    Height="450"
    mc:Ignorable="d">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal">
            <Button
                x:Name="FloatToolWindowButton"
                Margin="8,0,0,0"
                Click="FloatToolWindowButton_Click"
                Content="(1) Float Right ToolWindow" />
            <Button
                x:Name="CloseToolWindowButton"
                Margin="8,0,0,0"
                Click="CloseToolWindowButton_Click"
                Content="(2) Close Right ToolWindow" />
            <Button
                x:Name="ShowDialogButton"
                Margin="8,0,0,0"
                Click="ShowDialogButton_Click"
                Content="(3) Show Dialog" />
        </StackPanel>

        <docking:DockSite x:Name="MyDockSite" Grid.Row="1">
            <docking:SplitContainer>

                <!--  Workspace  -->
                <docking:Workspace>
                    <docking:TabbedMdiHost>
                        <docking:ToolWindowContainer>
                            <docking:ToolWindow
                                Title="Fixed"
                                CanAttach="False"
                                CanDragTab="False"
                                HasTitleBar="False" />
                        </docking:ToolWindowContainer>
                    </docking:TabbedMdiHost>
                </docking:Workspace>

                <docking:ToolWindowContainer>
                    <docking:ToolWindow Title="Right" DefaultDockSide="Right" />
                </docking:ToolWindowContainer>
            </docking:SplitContainer>
        </docking:DockSite>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace DockingWindowSample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ShowDialogButton_Click(object sender, RoutedEventArgs e)
        {
            var window = new Window { Title = "Sub Dialog", ResizeMode = ResizeMode.NoResize, Height = 100, Width = 200 };
            var button = new Button { Content = "(4) Show ToolWindow", HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center };
            button.Click += OnSubDialogButtonClicked;
            window.Content = button;
            window.ShowDialog();
        }

        private void OnSubDialogButtonClicked(object sender, RoutedEventArgs e)
        {
            var target = MyDockSite.ToolWindows.FirstOrDefault(x => x.Title == "Right");
            if (target != null)
            {
                target.Open();
            }
        }

        private void FloatToolWindowButton_Click(object sender, RoutedEventArgs e)
        {
            var target = MyDockSite.ToolWindows.FirstOrDefault(x => x.Title == "Right");
            if (target != null)
            {
                target.IsFloating = true;
            }
        }

        private void CloseToolWindowButton_Click(object sender, RoutedEventArgs e)
        {
            var target = MyDockSite.ToolWindows.FirstOrDefault(x => x.Title == "Right");
            if (target != null)
            {
                target.Close();
            }
        }
    }
}