private void BTN_Edit_Click(object sender, EventArgs e)
{
Customer customer = (Customer)LB_Customers.SelectedItem;
NewCustomer newCustomer = new NewCustomer();
newCustomer.TXT_Name.Text = customer.name;
newCustomer.TXT_Street.Text = customer.street;
newCustomer.TXT_Municipality.Text = customer.municipality;
newCustomer.TXT_btwNumber.Text = customer.BTWnumber;
newCustomer.editMode = true;
newCustomer.EditedCustomer += Refresh;
newCustomer.Show();
}