void OnLayout (object sender, LayoutEventArgs e)
{
_dataGridView.Width = Width - 50;
_dataGridView.Height = Height - _changeButton.Height * 2 - 50;
_changeButton.Top = _dataGridView.Height + _changeButton.Height * 2 - 15;
_changeButton.Left = Width / 2 - _changeButton.Width / 2;
}