private void DGCustomers_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
BuyerClass.ContractsForCustomer.Clear();
foreach (Cust_Price c in DGCustomers.SelectedItems)
{
BuyerClass.ContractsForCustomer = PlannerClass.ContractsByName_Populate(c.Client_Name);
}
DGContractsForCustomer.ItemsSource = BuyerClass.ContractsForCustomer;
}