Hi,

CellEditEnding won’t help here. Considering current cell lies in first row and first column, please try it this way instead:

//Keep grid in edit mode if user hits Enter/Tab key while editor is active
            this.c1FlexGrid.PrepareCellForEdit += (sender, e) => {
                if (e.Row == 0 && e.Column == 0)
                {
                    var b = e.Editor as Border;
                    var tb = b.Child as TextBox;
                    if (tb != null)
                        tb.KeyDown += (s1, e1) =>
                        {
                            if (e1.Key == Key.Enter || e1.Key == Key.Tab)
                                e1.Handled = true;
                        };
                }
            };

            //Cancel selection
            this.c1FlexGrid.SelectionChanging += (sender, e) =>
            {
                var flex = sender as C1.Silverlight.FlexGrid.C1FlexGrid;
                if (e.CellRange.IsSingleCell)
                {
                    if (flex.Selection.Row == 0 && flex.Selection.Column == 0)
                    {
                        e.Cancel = true;
                        flex.StartEditing(true);
                    }
                }
            };

Cheers,
~Anupam.