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Application.Windows Property

Gets the instantiated windows in an application.

Namespace:  System.Windows
Assembly:  PresentationFramework (in PresentationFramework.dll)
public WindowCollection Windows { get; }

Property Value

Type: System.Windows.WindowCollection
A WindowCollection that contains references to all window objects in the current AppDomain.

A Window reference is automatically added to Windows as soon as a window is instantiated on the user interface (UI) thread; windows that are created by worker threads are not added. A Window reference is automatically removed after its Closing event has been handled and before its Closed event is raised.

By default, the first item added to the Windows property becomes the MainWindow.

This property is available only from the thread that created the Application object.

The following example demonstrates how to enumerate the Windows property to build a top-level Windows menu, which is common to multiple-document interface (MDI) applications like Microsoft Excel, or multiple-instance Single Document Interface (SDI) applications like Microsoft Word.

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

namespace CSharp
    // Custom menu item that stores a reference to a window 
    public class WindowMenuItem : MenuItem
        public Window Window = null;
<Window x:Class="CSharp.MainWindow"
  Title="CSharp" Height="300" Width="300" Activated="MainWindow_Activated"
      <MenuItem Header="_File">
        <MenuItem Name="newWindowMenuItem" Click="newWindowMenuItem_Click" Header="_New Window"></MenuItem>
        <MenuItem Name="exitMenuItem" Click="exitMenuItem_Click" Header="E_xit"></MenuItem>
      <MenuItem Name="windowMenuItem" Header="_Window">
using System;
using System.Windows;
using System.Windows.Controls;

namespace CSharp
    public partial class MainWindow : Window
        public MainWindow()


        void MainWindow_Activated(object sender, EventArgs e)
            int windowCount = 0;
            foreach (Window window in Application.Current.Windows)
                WindowMenuItem menuItem = new WindowMenuItem();
                menuItem.Window = window;
                menuItem.Header = "_" + windowCount.ToString() + " Window " + windowCount.ToString();
                menuItem.Click += new RoutedEventHandler(menuItem_Click);

        void menuItem_Click(object sender, RoutedEventArgs e)
            WindowMenuItem menuItem = (WindowMenuItem)sender;

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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