private bool IsValidColumn(TreeListColumn column, GraphicsInfoArgs columnInfo)
 {
     return columnInfo != null && column.Fixed == FixedStyle.None &&
            ((!tree.ViewInfo.HasFixedLeft && columnInfo.Bounds.X > 0)
             || (tree.ViewInfo.HasFixedLeft && columnInfo.Bounds.X >= tree.ViewInfo.ViewRects.FixedLeft.Right));
 }
 protected override void DrawDividers(GraphicsInfoArgs e)
 {
     // base.DrawDividers(e);
 }