//show edit form
        private void Suppliers_EditClickedEventHandler(object sender, RoutedEventArgs e)
        {
            Supplier         supplier         = SuppliersDataGrid.SelectedItem as Supplier;
            Supplier_AddEdit editSupplierForm = new Supplier_AddEdit(Ctx, Suppliers, supplier);

            editSupplierForm.Show();
        }
        //show add form
        private void Suppliers_AddClickedEventHandler(object sender, RoutedEventArgs e)
        {
            Supplier_AddEdit addSupplierForm = new Supplier_AddEdit(Ctx, Suppliers);

            addSupplierForm.Show();
        }