[DefaultValue(null)]
public virtual PopupControl DropDownControl { get; set; }

<DefaultValue(Nothing)>
Public Overridable Property DropDownControl As PopupControl

using DevExpress.XtraEditors;
using DevExpress.XtraBars;

namespace WindowsFormsApp1
{
  public partial class XtraForm1 : DevExpress.XtraEditors.XtraForm
    {
    public XtraForm3()
        {
        InitializeComponent();

        BarManager barManager = new BarManager();
            barManager.Form = this;

            barManager.BeginUpdate();
            Bar bar1 = new Bar(barManager, "My Bar");
            bar1.DockStyle = BarDockStyle.Top;
            BarButtonItem buttonViewOutput = new BarButtonItem(barManager, "Zoom");
            bar1.AddItem(buttonViewOutput);
            barManager.EndUpdate();

            buttonViewOutput.ButtonStyle = BarButtonStyle.DropDown;
            buttonViewOutput.DropDownEnabled = true;

            Label scaleLabel = new Label();
            scaleLabel.Text = "Zoom to:";
            scaleLabel.Dock = DockStyle.Top;

            SpinEdit scaleSpin = new SpinEdit();
            scaleSpin.Dock = DockStyle.Bottom;
            scaleSpin.EditValue = 135;

            Label scaleSpinLabel = new Label();
            scaleSpinLabel.Width = 50;
            scaleSpinLabel.Padding = new Padding(0,10,0,0);
            scaleSpinLabel.Text = "Percent:";
            scaleSpinLabel.Dock = DockStyle.Left;

            RadioGroup scaleRadio = new RadioGroup();
            scaleRadio.Properties.Columns = 2;
            scaleRadio.Dock = DockStyle.Top;
            scaleRadio.Properties.Items.Add(new RadioGroupItem { Description="200%" });
            scaleRadio.Properties.Items.Add(new RadioGroupItem { Description = "100%" });
            scaleRadio.Properties.Items.Add(new RadioGroupItem { Description = "75%" });
            scaleRadio.Properties.Items.Add(new RadioGroupItem { Description = "Page width" });
            scaleRadio.Properties.Items.Add(new RadioGroupItem { Description = "Whole width" });

            PopupControlContainer container = new PopupControlContainer();
            container.Padding = new Padding(10);
            container.Height = 165;
            container.Width = 200;
            container.Manager = barManager1;
            container.Controls.Add(scaleSpin);
            container.Controls.Add(scaleSpinLabel);
            container.Controls.Add(scaleRadio);
            container.Controls.Add(scaleLabel);
            buttonViewOutput.DropDownControl = container;
        }
    }
}

Imports DevExpress.XtraEditors
Imports DevExpress.XtraBars

Namespace WindowsFormsApp1
  Partial Public Class XtraForm1
      Inherits DevExpress.XtraEditors.XtraForm

    Private Function XtraForm3() As Public
        InitializeComponent()

        Dim barManager As New BarManager()
            barManager.Form = Me

            barManager.BeginUpdate()
            Dim bar1 As New Bar(barManager, "My Bar")
            bar1.DockStyle = BarDockStyle.Top
            Dim buttonViewOutput As New BarButtonItem(barManager, "Zoom")
            bar1.AddItem(buttonViewOutput)
            barManager.EndUpdate()

            buttonViewOutput.ButtonStyle = BarButtonStyle.DropDown
            buttonViewOutput.DropDownEnabled = True

            Dim scaleLabel As New Label()
            scaleLabel.Text = "Zoom to:"
            scaleLabel.Dock = DockStyle.Top

            Dim scaleSpin As New SpinEdit()
            scaleSpin.Dock = DockStyle.Bottom
            scaleSpin.EditValue = 135

            Dim scaleSpinLabel As New Label()
            scaleSpinLabel.Width = 50
            scaleSpinLabel.Padding = New Padding(0,10,0,0)
            scaleSpinLabel.Text = "Percent:"
            scaleSpinLabel.Dock = DockStyle.Left

            Dim scaleRadio As New RadioGroup()
            scaleRadio.Properties.Columns = 2
            scaleRadio.Dock = DockStyle.Top
            scaleRadio.Properties.Items.Add(New RadioGroupItem With {.Description="200%"})
            scaleRadio.Properties.Items.Add(New RadioGroupItem With {.Description = "100%"})
            scaleRadio.Properties.Items.Add(New RadioGroupItem With {.Description = "75%"})
            scaleRadio.Properties.Items.Add(New RadioGroupItem With {.Description = "Page width"})
            scaleRadio.Properties.Items.Add(New RadioGroupItem With {.Description = "Whole width"})

            Dim container As New PopupControlContainer()
            container.Padding = New Padding(10)
            container.Height = 165
            container.Width = 200
            container.Manager = barManager1
            container.Controls.Add(scaleSpin)
            container.Controls.Add(scaleSpinLabel)
            container.Controls.Add(scaleRadio)
            container.Controls.Add(scaleLabel)
            buttonViewOutput.DropDownControl = container
    End Function
  End Class
End Namespace

PrintPreviewBarItem item = (PrintPreviewBarItem)form.PrintBarManager.GetBarItemByCommand(PrintingSystemCommand.ExportFile);
PopupMenu control = (PopupMenu)((DevExpress.XtraBars.BarButtonItem)(item)).DropDownControl;
BarButtonItem barItem = new BarButtonItem();

Dim item As PrintPreviewBarItem = CType(form.PrintBarManager.GetBarItemByCommand(PrintingSystemCommand.ExportFile), PrintPreviewBarItem)
Dim control As PopupMenu = CType((CType(item, DevExpress.XtraBars.BarButtonItem)).DropDownControl, PopupMenu)
Dim barItem As New BarButtonItem()