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UIElement.LostKeyboardFocus Event

Occurs when the keyboard is no longer focused on this element,.

Namespace:  System.Windows
Assembly:  PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

'Declaration
Public Event LostKeyboardFocus As KeyboardFocusChangedEventHandler
<object LostKeyboardFocus="KeyboardFocusChangedEventHandler" .../>

Implements

IInputElement.LostKeyboardFocus

Identifier field

LostKeyboardFocusEvent

Routing strategy

Bubbling

Delegate

KeyboardFocusChangedEventHandler

Because this event uses bubbling routing, the element that lost focus might be a child element instead of the element where the event handler is actually attached. Check the Source in the event data to determine the actual element that lost focus.

This event creates an alias for the Keyboard.LostKeyboardFocus attached event for this class, so that LostKeyboardFocus is part of the class members list when UIElement is inherited as a base element. Event handlers that are attached to the LostKeyboardFocus event are attached to the underlying Keyboard.LostKeyboardFocus attached event and receive the same event data instance.

This example shows how to change the color of an element when it gains and loses focus by using the GotFocus and LostFocus events.

This example consists of a Extensible Application Markup Language (XAML) file and a code-behind file.

The following XAML creates the user interface, which consists of two Button objects, and attaches event handlers for the GotFocus and LostFocus events to the Button objects.

<StackPanel>
  <StackPanel.Resources>
    <Style TargetType="{x:Type Button}">
      <Setter Property="Height" Value="20"/>
      <Setter Property="Width" Value="250"/>
      <Setter Property="HorizontalAlignment" Value="Left"/>
    </Style>
  </StackPanel.Resources>
  <Button
      GotFocus="OnGotFocusHandler"
      LostFocus="OnLostFocusHandler">Click Or Tab To Give Keyboard Focus</Button>
  <Button
      GotFocus="OnGotFocusHandler"
      LostFocus="OnLostFocusHandler">Click Or Tab To Give Keyborad Focus</Button>
</StackPanel>

The following code behind creates the GotFocus and LostFocus event handlers. When the Button gains keyboard focus, the Background of the Button is changed to red. When the Button loses keyboard focus, the Background of the Button is changed back to white.

Partial Public Class Window1
    Inherits Window

    Public Sub New()
        InitializeComponent()
    End Sub 

    'raised when Button gains focus. Changes the color of the Button to red. 
    Private Sub OnGotFocusHandler(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Dim tb As Button = CType(e.Source, Button)
        tb.Background = Brushes.Red
    End Sub 

    'raised when Button loses focus. Changes the color back to white. 
    Private Sub OnLostFocusHandler(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Dim tb As Button = CType(e.Source, Button)
        tb.Background = Brushes.White
    End Sub 
End Class

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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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