public MessageBoxImageOptions ImageOptions { get; }

Public ReadOnly Property ImageOptions As MessageBoxImageOptions

private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
  // Create and initialize an object with message box settings.
  XtraMessageBoxArgs args = new XtraMessageBoxArgs() {
    Caption = "Warning",
    Text = "Do you want to quit?",
    Buttons = new DialogResult[] { DialogResult.Yes, DialogResult.No }
    };
  // Assign a message box icon.
  args.ImageOptions.SvgImage = svgImageCollection1[0];
  args.ImageOptions.SvgImageSize = new Size(24, 24);
  // Display the message box and close the application if the user clicks "Yes".
  if (XtraMessageBox.Show(args) == DialogResult.No)
    e.Cancel = true;
}

Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
  ' Create and initialize an object with message box settings.
  Dim args As New XtraMessageBoxArgs() With {
    .Caption = "Warning",
    .Text = "Do you want to quit?",
    .Buttons = New DialogResult() { DialogResult.Yes, DialogResult.No }
  }
  ' Assign a message box icon.
  args.ImageOptions.SvgImage = svgImageCollection1(0)
  args.ImageOptions.SvgImageSize = New Size(24, 24)
  ' Display the message box and close the application if the user clicks "Yes".
  If XtraMessageBox.Show(args) = DialogResult.No Then
    e.Cancel = True
  End If
End Sub