public RadForm1()
        {
            InitializeComponent();

            DataTable dt = new DataTable();
            dt.Columns.Add("Id");
            dt.Columns.Add("Name");
            for (int i = 0; i < 10; i++)
            {
                dt.Rows.Add(i, "Item" + i); 
            }
            this.radGridView1.DataSource = dt; 
            this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill; 
             
            this.radGridView1.CellValidating += radGridView1_CellValidating;
        }

        private void radGridView1_CellValidating(object sender, CellValidatingEventArgs e)
        {
            if (e.Column.Index == 0 && e.ActiveEditor != null && e.Value + "" == "1")
            { 
                e.Cancel = true;
                RadMessageBox.Show("IncorrectValue");
            }
        }

        public class CustomGridView : RadGridView
        {
            public override string ThemeClassName  
            { 
                get 
                { 
                    return typeof(RadGridView).FullName;  
                }
            }

            protected override void OnMouseDown(MouseEventArgs e)
            {
             RadScrollBarElement scrollbar=   this.GridViewElement.ElementTree.GetElementAtPoint ( e.Location) as RadScrollBarElement;
             if (scrollbar!=null && this.IsInEditMode)
             {
                    this.EditorManager.CloseEditorWhenValidationFails = false;
                    this.EditorManager.CloseEditor();
                    return;
             }
                base.OnMouseDown(e);
            }
        }