Some design time problems have been fixed. If you use the Syncfusion Update Notifier, you will be automatically notified when a patch is published.
To place "(null)" in empty cells, you can use the QueryCellStyleInfo event.
private void gridGroupingControl1_QueryCellStyleInfo(object sender, GridTableCellStyleInfoEventArgs e)
{
if((e.TableCellIdentity.TableCellType == GridTableCellType.RecordFieldCell
|| e.TableCellIdentity.TableCellType == GridTableCellType.AlternateRecordFieldCell)
&& e.Style.CellValue == DBNull.Value)
{
e.Style.Text = "(null)";
}
}