How to close a window from the user control inside?
<p>I've got a WPF program and at some point I open a window:</p>

<pre><code>    public object testCommand()
    {
        Window window = new Window
        {
            Title = "My User Control Dialog",
            Content = new OKMessageBox("Error Message"),
            SizeToContent = SizeToContent.WidthAndHeight,
            ResizeMode = ResizeMode.NoResize
        };
        window.WindowStartupLocation = WindowStartupLocation.CenterScreen;
        window.ShowDialog();

        return null;
    }
</code></pre>

<p>User Control XAML:</p>

<pre><code>&lt;UserControl x:Class="SolidX.Base.MessageBoxes.OKMessageBox"
             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:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:SolidX.Base.MessageBoxes"
             xmlns:viewProperties="clr-namespace:AppResources.Properties;assembly=AppResources"
             mc:Ignorable="d" 
             d:DesignHeight="150" d:DesignWidth="400"&gt;
    &lt;Grid&gt;
        &lt;TextBlock x:Name="textMessage" Margin="10"/&gt;
        &lt;Grid Height="Auto" VerticalAlignment="Bottom"&gt;
            &lt;Grid.RowDefinitions&gt;
                &lt;RowDefinition/&gt;
                &lt;RowDefinition/&gt;
            &lt;/Grid.RowDefinitions&gt;
            &lt;CheckBox Content="Don't show this again" HorizontalAlignment="Right" Margin="5,5,10,5"/&gt;
            &lt;StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Right"&gt;
                &lt;Button x:Name="btnOk" Content="{x:Static viewProperties:Resources.Common_OK}" Height="25" VerticalAlignment="Center" Width="90" Margin="5"/&gt;
            &lt;/StackPanel&gt;
        &lt;/Grid&gt;
    &lt;/Grid&gt;
&lt;/UserControl&gt;
</code></pre>

<p>User Control Code-behind:</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace SolidX.Base.MessageBoxes
{
    /// &lt;summary&gt;
    /// Interaction logic for OKMessageBox.xaml
    /// &lt;/summary&gt;
    public partial class OKMessageBox : UserControl
    {
        public OKMessageBox(string Message)
        {
            InitializeComponent();
            textMessage.Text= Message;
        }
    }
}
</code></pre>

<p>And in my user control, I am trying to have buttons that close the window (currently, setting <code>Button.IsCancel = true;</code> works, but I want this to be a reusable option - essentially making my own <code>this.Close;</code>).</p>

<p>I tried this (as suggested by a couple other StackOverflow answers) in the code-behind for my usercontrol but to no avail (<code>parentWindow</code> is always null):</p>

<pre><code>var parentWindow = Window.GetWindow(this);
parentWindow.Close();
</code></pre>