How to customize the ToolTip for a TreeList cell

Description:
Is it possible to display a custom tooltip for a node cell?

Answer:
Yes, it's possible. You should drop the ToolTipController onto a form, set the TreeList's ToolTipController property and handle the ToolTipController.GetActiveObjectInfo event.

C#
using DevExpress.XtraTreeList;  
using DevExpress.XtraTreeList.ViewInfo;  

private void toolTipController1_GetActiveObjectInfo(object sender, DevExpress.Utils.ToolTipControllerGetActiveObjectInfoEventArgs e) {  
   if(e.SelectedControl is DevExpress.XtraTreeList.TreeList) {  
       TreeList tree = (TreeList)e.SelectedControl;  
       TreeListHitInfo hit = tree.CalcHitInfo(e.ControlMousePosition);  
       if(hit.HitInfoType == HitInfoType.Cell) {  
           object cellInfo = new TreeListCellToolTipInfo(hit.Node, hit.Column, null);  
           string toolTip = string.Format("{0} (Column: {1}, Node ID: {2})", hit.Node[hit.Column], hit.Column.Caption, hit.Node.Id);  
           e.Info =  new DevExpress.Utils.ToolTipControlInfo(cellInfo, toolTip);  
       }  
   }  
}  

Visual Basic
Imports DevExpress.XtraTreeList  
Imports DevExpress.XtraTreeList.ViewInfo  

Private Sub toolTipController1_GetActiveObjectInfo(ByVal sender As Object, ByVal e As DevExpress.Utils.ToolTipControllerGetActiveObjectInfoEventArgs) Handles toolTipController1.GetActiveObjectInfo  
   If TypeOf e.SelectedControl Is DevExpress.XtraTreeList.TreeList Then  
       Dim tree As TreeList = CType(e.SelectedControl, TreeList)  
       Dim hit As TreeListHitInfo = tree.CalcHitInfo(e.ControlMousePosition)  
       If hit.HitInfoType = HitInfoType.Cell Then  
           Dim cellInfo As Object = New TreeListCellToolTipInfo(hit.Node, hit.Column, Nothing)  
           Dim toolTip As String = String.Format("{0} (Column: {1}, Node ID: {2})", hit.Node(hit.Column), hit.Column.Caption, hit.Node.Id)  
           e.Info = New DevExpress.Utils.ToolTipControlInfo(cellInfo, toolTip)  
       End If  
   End If  
End Sub  

See Also:
Showing a hint for a grid cell even if its content is completely visible
How to get multi-line tooltips with a specific width
How to programmatically display a tooltip for a control via the ToolTipController component
How to display a hint for an active editor within the XtraGrid
How to display hints only for particular cells
ToolTipController class