Application.Activated Event

Occurs when an application becomes the foreground application.

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

'Declaration
Public Event Activated As EventHandler
'Usage
Dim instance As Application 
Dim handler As EventHandler 

AddHandler instance.Activated, handler
<object Activated="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. For more information, including an example that illustrates this dependency, see Application Activation and Deactivation Sample.

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" />
using System; // EventArgs 
using System.Windows; // Application 

namespace SDKSample
{
    public partial class App : Application
    {
        bool isApplicationActive;

        void App_Activated(object sender, EventArgs e)
        {
            // Application activated 
            this.isApplicationActive = true;
        }

        void App_Deactivated(object sender, EventArgs e)
        {
            // Application deactivated 
            this.isApplicationActive = false;
        }
    }
}

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
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft