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WindowInteropHelper Class

Assists interoperation between Windows Presentation Foundation (WPF) and Win32 code.

Namespace:  System.Windows.Interop
Assembly:  PresentationFramework (in PresentationFramework.dll)

public sealed class WindowInteropHelper
You cannot directly create an instance of this class in XAML.

Members of this class allows the caller to have internal access to the Win32 HWND and the parent HWND of a WPF Window.  The proper security checks are performed by those members.

Use this class whenever you need a more specific object based on its HWND.

An example scenario is if you need to host a WPF dialog box in a Win32 application. Initialize the WindowInteropHelper  with a WPF window object for the dialog. You can then get the WPF window's handle (HWND) from the Handle property and specify the owner for the WPF window with the Owner property. The following code example shows how to use WindowInteropHelper when hosting a WPF dialog box in a Win32 application.

WindowInteropHelper wih = new WindowInteropHelper(myDialog);
wih.Owner = ownerHwnd;

Another scenario supported by this class is to obtain a HwndSource object from a WPF Window object. The HwndSource enables direct processing of Win32 messages through the AddHook method. By using HwndSource and AddHook in place of a Window you can still handle messages that have no equivalent or handling in WPF. Create a WindowInteropHelper  with the Window source , then call Handle on the WindowInteropHelper to get from HWND to HwndSource.


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

.NET Framework

Supported in: 3.5, 3.0