private void btnDatum_Click(object sender, EventArgs e)
 {
     DatumForm form = new DatumForm();
     ControlsToData();
     form.Datum = _doubleValue;
     if (DialogResult.OK == form.ShowDialog())
     {
         _doubleValue = form.Datum as @double;
         DataToControls();
     }
 }
        private void otherAttributes_CellContentClick( object sender, DataGridViewCellEventArgs e )
        {
            var senderGrid = (DataGridView) sender;

            if (senderGrid.Columns[e.ColumnIndex] is DataGridViewButtonColumn &&
                e.RowIndex >= 0)
            {
                var form = new DatumForm();
                if (DialogResult.OK == form.ShowDialog())
                {
                    DatumType value = form.Datum;
                    senderGrid.Rows[e.RowIndex].Cells[1].Value = value.ToString();
                }
            }
        }