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how-to-close-window-dialog-box.md

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How to close a window
Learn about how to close a window or dialog box in Windows Foundation Presentation (WPF). You'll also learn how to return a result from the window or dialog box.
03/24/2021
csharp
vb
modeless dialog boxes [WPF]
modal dialog boxes [WPF]
dialog boxes [WPF]
message boxes [WPF]

How to close a window or dialog box (WPF .NET)

In this article, you'll learn about the different ways to close a window or dialog box. A user can close a window by using the elements in the non-client area, including the following:

  • The Close item of the System menu.
  • Pressing ALT + F4.
  • Pressing the Close button.
  • Pressing ESC when a button has the xref:System.Windows.Controls.Button.IsCancel%2A property set to true on a modal window.

When designing a window, provide more mechanisms to the client area to close a window. Some of the common design elements on a window that are used to close it include the following:

  • An Exit item in the File menu, typically for main application windows.
  • A Close item in the File menu, typically on a secondary application window.
  • A Cancel button, typically on a modal dialog box.
  • A Close button, typically on a modeless dialog box.

Important

Once a window is closed, the same object instance can't be used to reopen the window.

For more information about the life of a window, see Overview of WPF windows: Window lifetime.

Close a modal window

When closing a window that was opened with the xref:System.Windows.Window.ShowDialog%2A method, set the xref:System.Windows.Window.DialogResult property to either true or false to indicate an "accepted" or "canceled" state, respectively. As soon as the DialogResult property is set to a value, the window closes. The following code demonstrates setting the DialogResult property:

:::code language="csharp" source="snippets/how-to-close-window-dialog-box/csharp/Menus.xaml.cs" id="CloseDialog"::: :::code language="vb" source="snippets/how-to-close-window-dialog-box/vb/Menus.xaml.vb" id="CloseDialog":::

You can also call the xref:System.Windows.Window.Close%2A method. If the Close method is used, the xref:System.Windows.Window.DialogResult property is set to false.

Once a window has been closed, it can't be reopened with the same object instance. If you try to show the same window, a xref:System.InvalidOperationException is thrown. Instead, create a new instance of the window and open it.

Close a modeless window

When closing a window that was opened with the xref:System.Windows.Window.Show%2A method, use the xref:System.Windows.Window.Close%2A method. The following code demonstrates closing a modeless window:

:::code language="csharp" source="snippets/how-to-close-window-dialog-box/csharp/Menus.xaml.cs" id="CloseNormal"::: :::code language="vb" source="snippets/how-to-close-window-dialog-box/vb/Menus.xaml.vb" id="CloseNormal":::

Close with IsCancel

The xref:System.Windows.Controls.Button.IsCancel?displayProperty=nameWithType property can be set to true to enable the ESC key to automatically close the window. This only works when the window is opened with xref:System.Windows.Window.ShowDialog%2A method.

:::code language="xaml" source="snippets/how-to-close-window-dialog-box/csharp/Window1.xaml" id="CancelButton":::

Hide a window

Instead of closing a window, a window can be hidden with the xref:System.Windows.Window.Hide%2A method. A hidden window can be reopened, unlike a window that has been closed. If you're going to reuse a window object instance, hide the window instead of closing it. The following code demonstrates hiding a window:

:::code language="csharp" source="snippets/how-to-close-window-dialog-box/csharp/Menus.xaml.cs" id="Hide"::: :::code language="vb" source="snippets/how-to-close-window-dialog-box/vb/Menus.xaml.vb" id="Hide":::

Cancel close and hide

If you've designed your buttons to hide a window instead of closing it, the user can still bypass this and close the window. The Close item of the system menu and the Close button of the non-client area of the window, will close the window instead of hiding it. Consider this scenario when your intent is to hide a window instead of closing it.

Caution

If a window is shown modally with xref:System.Windows.Window.ShowDialog%2A, the xref:System.Windows.Window.DialogResult property will be set to null when the window is hidden. You'll need to communicate state back to the calling code by adding your own property to the window.

When a window is closed, the xref:System.Windows.Window.Closing event is raised. The handler is passed a xref:System.ComponentModel.CancelEventArgs, which implements the xref:System.ComponentModel.CancelEventArgs.Cancel property. Set that property to true to prevent a window from closing. The following code demonstrates how to cancel the closure and instead hide the window:

:::code language="csharp" source="snippets/how-to-close-window-dialog-box/csharp/Margins.xaml.cs" id="CancelAndHide"::: :::code language="vb" source="snippets/how-to-close-window-dialog-box/vb/Margins.xaml.vb" id="CancelAndHide":::

There may be times where you don't want to hide a window, but actually prevent the user from closing it. For more information, see Overview of WPF windows: Cancel window closure.

See also

  • Overview of WPF windows
  • Dialog boxes overview
  • How to open a window or dialog box
  • xref:System.Windows.Window.Close?displayProperty=fullName
  • xref:System.Windows.Window.Closing?displayProperty=fullName
  • xref:System.Windows.Window.DialogResult?displayProperty=fullName
  • xref:System.Windows.Window.Hide?displayProperty=fullName
  • xref:System.Windows.Window.Show?displayProperty=fullName
  • xref:System.Windows.Window.ShowDialog?displayProperty=fullName