Application.Activated Event

 
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Occurs when an application becomes the foreground application.

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

Public Event Activated As EventHandler

A Windows Presentation Foundation (WPF) application that has one or more open windows is activated (becomes the foreground application) when one of the windows is activated for the first time since the application was launched, or when one of the windows is activated while the application is inactive: Specifically, activation occurs when:

  • An application opens its first window.

  • A user switches to the application by using ALT+TAB or by using Task Manager.

  • A user clicks the taskbar button for one of the windows in an application.

Applications that need to detect when they activate can handle the Activated event.

After an application is first activated, it may be deactivated and reactivated many times during its lifetime. If an application's behavior or state depends on its activation state, it can handle both Activated and Deactivated events to determine which activation state it's in.

Once an application becomes active, Activated will not be raised again until the application is deactivated, irrespective of how many windows within an application are activated while the application is active.

Activated is not raised for XAML browser applications (XBAPs).

The following example shows how to detect when a standalone application activates and deactivates.

<Application 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  x:Class="SDKSample.App"
  StartupUri="MainWindow.xaml"
  Activated="App_Activated" 
  Deactivated="App_Deactivated" />

Imports Microsoft.VisualBasic
Imports System ' EventArgs
Imports System.Windows ' Application

Namespace SDKSample
	Partial Public Class App
		Inherits Application
		Private isApplicationActive As Boolean

		Private Sub App_Activated(ByVal sender As Object, ByVal e As EventArgs)
			' Application activated
			Me.isApplicationActive = True
		End Sub

		Private Sub App_Deactivated(ByVal sender As Object, ByVal e As EventArgs)
			' Application deactivated
			Me.isApplicationActive = False
		End Sub
	End Class
End Namespace

.NET Framework
Available since 3.0
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