OnSetEditText is one event you could use:
procedure TForm1.StringGrid1SetEditText(Sender: TObject; ACol,
ARow: Integer; const Value: String);
var i : integer; Sum:single;
begin
Sum:=0;
for i := 1 to StringGrid1.RowCount do
try
if StringGrid1.Cells[ACol,i] <> '' then
Sum:= Sum + StrToFloat( StringGrid1.Cells[ACol,i]);
except
// ignore any errors in conversion
end;
Label1.Caption := FloatToStr(Sum);
end;
That works in D7, there should be similar things in other versions of Delphi.