private void StockInUI_Load(object sender, EventArgs e)
{
DataTable cadt = stockInManager.GetCategoryStockInBindingSource();
categoryStockInBindingSource.DataSource = cadt;
categoryStockInComboBox.SelectedValue = -1;
messageLabel2.Text = "";
messageLabel.Text = "";
timer1.Start();
dateLabel.Text = DateTime.Now.ToLongDateString();
timeLabel.Text = DateTime.Now.ToLongTimeString();
}