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ComboBox.DropDown Event

Occurs when the drop-down portion of a ComboBox is shown.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
Public Event DropDown As EventHandler

For more information about handling events, see Consuming Events.

The following code example demonstrates how to initialize a ComboBox control by setting the text property and using the AddRange method to populate the ComboBox. It also demonstrates handling the DropDown event. To run the example, paste the following code in a form and call the InitializeComboBox method in the form's constructor or Load event.

' Declare ComboBox1. 
Friend WithEvents ComboBox1 As System.Windows.Forms.ComboBox

' Initialize ComboBox1. 
Private Sub InitializeComboBox()
    Me.ComboBox1 = New ComboBox
    Me.ComboBox1.Location = New System.Drawing.Point(128, 48)
    Me.ComboBox1.Name = "ComboBox1" 
    Me.ComboBox1.Size = New System.Drawing.Size(100, 21)
    Me.ComboBox1.TabIndex = 0
    Me.ComboBox1.Text = "Typical" 
    Dim installs() As String = New String() _
        {"Typical", "Compact", "Custom"}
End Sub 

' Handles the ComboBox1 DropDown event. If the user expands the   
' drop-down box, a message box will appear, recommending the 
' typical installation. 
Private Sub ComboBox1_DropDown _ 
    (ByVal sender As Object, ByVal e As System.EventArgs) _ 
    Handles ComboBox1.DropDown
    MessageBox.Show("Typical installation is strongly recommended.", _
    "Install information", MessageBoxButtons.OK, MessageBoxIcon.Information)
End Sub

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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