using DevExpress.XtraTreeList;
using DevExpress.XtraTreeList.Columns;
// ...
TreeListColumn column = treeList1.Columns["Budget"];
column.SummaryFooter = SummaryItemType.Sum;
column.SummaryFooterStrFormat = "Total: {0:c0}";
column.RowFooterSummary = SummaryItemType.Sum;
column.RowFooterSummaryStrFormat = "Subtotal: {0:c0}";

Imports DevExpress.XtraTreeList
Imports DevExpress.XtraTreeList.Columns
' ...
Dim Column As TreeListColumn = TreeList1.Columns("Budget")
Column.SummaryFooter = SummaryItemType.Sum
Column.SummaryFooterStrFormat = "Total: {0:c0}"
Column.RowFooterSummary = SummaryItemType.Sum
Column.RowFooterSummaryStrFormat = "Subtotal: {0:c0}"

using DevExpress.XtraTreeList;
using DevExpress.XtraTreeList.Columns;
// ...
TreeListColumn column = treeList1.Columns["LastOrder"];
column.SummaryFooter = SummaryItemType.Max;
column.SummaryFooterStrFormat = "Maximum month: {0:MMMM yyyy}";

Imports DevExpress.XtraTreeList
Imports DevExpress.XtraTreeList.Columns
' ...
Dim Column As TreeListColumn = TreeList1.Columns("LastOrder")
Column.SummaryFooter = SummaryItemType.Max
Column.SummaryFooterStrFormat = "Last month: {0:MMMM yyyy}"

private void treeList1_CustomDrawRowFooterCell(object sender, DevExpress.XtraTreeList.CustomDrawRowFooterCellEventArgs e) {
   if (e.Text == String.Empty || e.Column.Caption != "Budget") return;
         
   Brush brush;
   Border3DStyle borderStyle;
   // obtaining the summary value
   int summaryValue = Convert.ToInt32(e.Text);
   // specifying style characteristics for values outside the range
   if (summaryValue > 1000000) {
      brush = new LinearGradientBrush(e.Bounds, Color.FromArgb(0, 255, 128,0), Color.FromArgb(100, Color.Red), LinearGradientMode.Vertical);
      borderStyle = Border3DStyle.RaisedInner;
   }
   else {
      brush = new LinearGradientBrush(e.Bounds, Color.FromArgb(100, Color.Blue), Color.FromArgb(0, 255, 128,0), LinearGradientMode.Vertical);
      borderStyle = Border3DStyle.SunkenOuter;
   }
   // filling the background and painting borders
   using(brush) {
      e.Graphics.FillRectangle(brush, e.Bounds);
   }
   ControlPaint.DrawBorder3D(e.Graphics, e.Bounds, borderStyle);
   // formatting and painting the string
   string outText = string.Format("Subtotal: {0:c0}", summaryValue);
   e.Graphics.DrawString(outText, e.Appearance.Font, e.Appearance.GetForeBrush(e.Cache), e.Bounds, e.Appearance.GetStringFormat());
   // prohibiting default painting
   e.Handled = true;
}

Private Sub TreeList1_CustomDrawRowFooterCell(ByVal sender As Object, ByVal e As DevExpress.XtraTreeList.CustomDrawRowFooterCellEventArgs) _
Handles TreeList1.CustomDrawRowFooterCell
   If e.Text = String.Empty Or e.Column.Caption <> "Budget" Then Exit Sub

   Dim CellBrush As Brush
   Dim CellBorderStyle As Border3DStyle
   ' obtaining the summary value
   Dim SummaryValue As Integer = Convert.ToInt32(e.Text)
   ' specifying style characteristics for values outside the range
   If SummaryValue > 1000000 Then
      CellBrush = New LinearGradientBrush(e.Bounds, Color.FromArgb(0, 255, 128, 0), Color.FromArgb(100, Color.Red), LinearGradientMode.Vertical)
      CellBorderStyle = Border3DStyle.RaisedInner
   Else
      CellBrush = New LinearGradientBrush(e.Bounds, Color.FromArgb(100, Color.Blue), Color.FromArgb(0, 255, 128, 0), LinearGradientMode.Vertical)
      CellBorderStyle = Border3DStyle.SunkenOuter
   End If
   ' filling the background and painting borders
   e.Graphics.FillRectangle(CellBrush, e.Bounds)
   CellBrush.Dispose()
   ControlPaint.DrawBorder3D(e.Graphics, e.Bounds, CellBorderStyle)
   ' formatting and painting the string
   Dim OutText As String = String.Format("Subtotal: {0:c0}", SummaryValue)
   Dim BoundsF As New RectangleF(e.Bounds.X, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height)
   e.Graphics.DrawString(OutText, e.Appearance.Font, e.Appearance.GetForeBrush(e.Cache), BoundsF, e.Appearance.GetStringFormat())
   ' prohibiting default painting
   e.Handled = True
End Sub