procedure TJvDBGrid.ChangeBoolean(const FieldValueChange: Shortint);
// FieldValueChange = 9 -> invert, 0 -> check (true), -1 -> uncheck (false)
begin
  if Assigned(FBooleanFieldToEdit) and BooleanEditor then
  begin
    DataLink.Edit;
    if DataLink.Editing then   //<-------------- Added this Line
    begin
      if FBooleanFieldToEdit.IsNull or (FieldValueChange <> JvGridBool_INVERT) then
      begin
        if FBooleanFieldToEdit.DataType = ftBoolean then
          FBooleanFieldToEdit.Value := (FieldValueChange = JvGridBool_CHECK)
        else
          FBooleanFieldToEdit.Value := FieldValueChange + 1;
      end
      else
        if FBooleanFieldToEdit.DataType = ftBoolean then
          FBooleanFieldToEdit.Value := not FBooleanFieldToEdit.AsBoolean
        else
          FBooleanFieldToEdit.Value := 1 - Abs(FBooleanFieldToEdit.AsInteger);
      InvalidateCell(Col, Row);
    end; //<-------------- Added this Line
  end;
  FBooleanFieldToEdit := nil;
end;