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Form.Deactivate Event

Occurs when an active form becomes inactive. This API is obsolete. For information about how to develop ASP.NET mobile applications, see the Web site.

Namespace:  System.Web.UI.MobileControls
Assembly:  System.Web.Mobile (in System.Web.Mobile.dll)

public event EventHandler Deactivate
<asp:Form OnDeactivate="EventHandler" />

A form becomes inactive under the following circumstances:

  • When the ActiveForm property of the page is programmatically set to another form.

  • When the user navigates to a form through a Link control whose target is a form.

If neither of these actions occurs, the active form will never receive a Deactivate event. This event's position in the event chain makes it very important in resetting the child controls, data set, or global variables.

The following code example demonstrates how to trap the Deactivate event to clear the SelectionList. This example is part of a larger example for the Form overview.

// When Form1 is deactivated
private void Form1_Deactivate(object sender, EventArgs e)

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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