项目
11/18/2011

AutoCompleteBox.OnDropDownOpening Method

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Namespace: System.Windows.Controls
Assembly: System.Windows.Controls.Input (in System.Windows.Controls.Input.dll)

Syntax

'Declaration
Protected Overridable Sub OnDropDownOpening ( _
    e As RoutedPropertyChangingEventArgs(Of Boolean) _
)

protected virtual void OnDropDownOpening(
    RoutedPropertyChangingEventArgs<bool> e
)

Parameters

e
Type: System.Windows.Controls.RoutedPropertyChangingEventArgs<Boolean>
A RoutedPropertyChangingEventArgs<T> that contains the event data.

Remarks

The DropDownOpening event occurs when the IsDropDownOpen property is changing from false to true.

Raising an event invokes the event handler through a delegate. The OnDropDownOpening method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When overriding OnDropDownOpening in a derived class, be sure to call the base class’s OnDropDownOpening method so that registered delegates receive the event.

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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