How to create custom ComboBox control like the ComboBoxAutoComplete?

void ButtonEditExt_TextChanged(object sender, EventArgs e)
{
    if (!this.DesignMode && this.autocomplete.DataSource != null)
    {
        this.autocomplete.ActiveFocusControl = this.TextBox;
        // Shows the autoCompletePopup.
        this.autocomplete.ProcessAutoComplete(this.TextBox.Text, string.Empty, Point.Empty);
    }
}
void buttonEditChildButton1_Click(object sender, EventArgs e)
{
    if (this.autocomplete.DataSource != null && !this.DesignMode)
    {
        this.autocomplete.ActiveFocusControl = this.TextBox;
        // Shows the autoCompletePopup.
        this.autocomplete.ProcessAutoComplete(this.TextBox.Text, string.Empty, Point.Empty);
    }
}
private object m_DataSource = null;
/// <summary>
/// Gets/sets the DataSource for the ButtonEditExt.
/// </summary>
public object DataSource
{
    get { return m_DataSource; }
    set
    {
        if (this.m_DataSource != value)
        {
            this.m_DataSource = value;
            //Changes parent form of the UserControl.
            this.autocomplete.ParentForm = this.ParentForm;
            this.autocomplete.DataSource = value;
            // Sets the AutoComplete Mode.
            this.autocomplete.SetAutoComplete(this.TextBox, AutoCompleteModes.MultiSuggestExtended);
        }
    }
}
private string displayMember = string.Empty;
/// <summary>
/// Gets/Sets the DisplayMember for the ButtonEditExt.
/// </summary>
public String DisplayMember
{
    get { return displayMember; }
    set
    {
        this.displayMember = value;
        if(this.displayMember != string.Empty)
            this.autocomplete.RefreshColumns();
        foreach(AutoCompleteDataColumnInfo column in this.autocomplete.Columns)
        {
            if(column.ColumnName == value)
            {
                column.Visible = true;
            }
            else
            {
                column.Visible = false;
            }
        }
    }
}

Private Sub ButtonEditExt_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
 If (Not Me.DesignMode) AndAlso Me.autocomplete.DataSource IsNot Nothing Then
  Me.autocomplete.ActiveFocusControl = Me.TextBox
  'Shows the autoCompletePopup.
  Me.autocomplete.ProcessAutoComplete(Me.TextBox.Text, String.Empty, Point.Empty)
 End If
End Sub
Private Sub buttonEditChildButton1_Click(ByVal sender As Object, ByVal e As EventArgs)
 If Me.autocomplete.DataSource IsNot Nothing AndAlso (Not Me.DesignMode) Then
  Me.autocomplete.ActiveFocusControl = Me.TextBox
  'Shows the autoCompletePopup.
  Me.autocomplete.ProcessAutoComplete(Me.TextBox.Text, String.Empty, Point.Empty)
 End If
End Sub
Private m_DataSource As Object = Nothing
''' <Summary>.
''' Gets/sets the DataSource for the ButtonEditExt.
''' </Summary>.
Public Property DataSource() As Object
 Get
  Return m_DataSource
 End Get
 Set(ByVal value As Object)
  If Me.m_DataSource IsNot value Then
   Me.m_DataSource = value
   'Changes parent form of the UserControl.
   Me.autocomplete.ParentForm = Me.ParentForm
   Me.autocomplete.DataSource = value
   ' Sets the AutoComplete Mode.
   Me.autocomplete.SetAutoComplete(Me.TextBox, AutoCompleteModes.MultiSuggestExtended)
  End If
 End Set
End Property
Private displayMember_Renamed As String = String.Empty
''' <Summary>.
''' Gets/Sets the DisplayMember for the ButtonEditExt.
''' </Summary>.
Public Property DisplayMember() As String
 Get
  Return displayMember_Renamed
 End Get
 Set(ByVal value As String)
  Me.displayMember_Renamed = value
  If Me.displayMember_Renamed <> String.Empty Then
   Me.autocomplete.RefreshColumns()
  End If
  For Each column As AutoCompleteDataColumnInfo In Me.autocomplete.Columns
   If column.ColumnName = value Then
    column.Visible = True
   Else
    column.Visible = False
   End If
  Next column
 End Set
End Property