ComboBox.DropDownOpened Evento

Definizione

Spazio dei nomi:

System.Windows.Controls

Assembly:

PresentationFramework.dll

Si verifica quando l'elenco a discesa della casella combinata si apre.

public:
 event EventHandler ^ DropDownOpened;

public event EventHandler DropDownOpened;

member this.DropDownOpened : EventHandler 

Public Custom Event DropDownOpened As EventHandler 

Tipo evento

EventHandler

Esempio

Nell'esempio seguente viene illustrato come assegnare gestori eventi e gestire gli DropDownOpened eventi e DropDownClosed .

<ComboBox Name="cb" StaysOpenOnEdit="true" IsEditable="true" DropDownOpened="OnDropDownOpened" 
        DropDownClosed="OnDropDownClosed">

void OnDropDownOpened(object sender, EventArgs e)
{
    if (cb.IsDropDownOpen == true)
    {
        cb.Text = "Combo box opened";
    }
}

void OnDropDownClosed(object sender, EventArgs e)
{
    if (cb.IsDropDownOpen == false)
    {
        cb.Text = "Combo box closed";
    }
}

Private Sub OnDropDownOpened(ByVal Sender As Object, ByVal e As EventArgs)

    If (cb.IsDropDownOpen = True) Then
        cb.Text = "Combo box opened"
    End If

End Sub

Private Sub OnDropDownClosed(ByVal Sender As Object, ByVal e As EventArgs)

    If (cb.IsDropDownOpen = False) Then
        cb.Text = "Combo box closed"
    End If

End Sub