[DXCategory("CustomDraw")]
public event CustomDrawNodeIndicatorEventHandler CustomDrawNodeIndicator

<DXCategory("CustomDraw")>
Public Event CustomDrawNodeIndicator As CustomDrawNodeIndicatorEventHandler

using System.Drawing;
using System.Drawing.Drawing2D;
using DevExpress.XtraTreeList;

private void treeList1_CustomDrawNodeIndicator(object sender, 
CustomDrawNodeIndicatorEventArgs e) {
    // Fill background with a linear gradient brush
    Brush backBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightSkyBlue,
      Color.Cyan, LinearGradientMode.Vertical);
    e.Cache.FillRectangle(backBrush, e.Bounds);
    // Paint borders
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds);

    // Calculate image position and painting it
    if (e.ImageIndex > -1)
    {
        Image indImage = (sender as TreeList).Painter.IndicatorImages.Images[e.ImageIndex];
        int imageLeft = e.Bounds.Left + (e.Bounds.Width - indImage.Width) / 2;
        int imageTop = e.Bounds.Top + (e.Bounds.Height - indImage.Height) / 2;
        e.Cache.DrawImage(indImage, new Point(imageLeft, imageTop));
    }

    // Prohibit default painting
    e.Handled = true;
}

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports DevExpress.XtraTreeList

Private Sub TreeList1_CustomDrawNodeIndicator(ByVal sender As Object, _
ByVal e As CustomDrawNodeIndicatorEventArgs) Handles TreeList1.CustomDrawNodeIndicator
    ' Fill background with a linear gradient brush
    Dim BackBrush = e.Cache.GetGradientBrush(e.Bounds, Color.LightSkyBlue,
                                             Color.Cyan, LinearGradientMode.Vertical)
    e.Cache.FillRectangle(BackBrush, e.Bounds)
    ' Paint borders
    e.Cache.DrawRectangle(e.Cache.GetPen(Color.LightGray), e.Bounds)

    ' Calculate image position and painting it
    If e.ImageIndex > -1 Then
        Dim IndImage As Image = sender.Painter.IndicatorImages.Images(e.ImageIndex)
        Dim ImageLeft As Integer = e.Bounds.Left + (e.Bounds.Width - IndImage.Width) / 2
        Dim ImageTop As Integer = e.Bounds.Top + (e.Bounds.Height - IndImage.Height) / 2
        e.Cache.DrawImage(IndImage, New Point(ImageLeft, ImageTop))
    End If

    ' Prohibit default painting
    e.Handled = True
End Sub