I'm unsure if this is user error or not, but if I drop a FNCDataGrid on a VCL form and then set the selection mode to gsmSingleRow. Then I drop a button on the form with the following code in the onClick event showmessage(TMSFNCDataGrid1.SelectedRowCount.ToString), then the answer is always 1, regardless of if there is a selection or not. If I set the selection mode to gsmDisjunctRow then the output is correct even if nothing is selected. Is the Grid reporting an incorrect value in the former example or is there something I need to do to get it to report the correct value?
TMSFNCDataGridRenderer should check if Selection.StartCell.Row and/or Selection.StopCell.Row = -1. Both are -1 when there's no selection.
BTW, it should be implemented with this -1 check and a subtraction. No need for a loop at that point.
Thanks for reporting, we have fixed the issue, next version will address this.