private void ContractorList_PreviewMouseDoubleClick(object sender, MouseButtonEventArgs e)
{
NewContractor form = new NewContractor((Contractor)ContractorList.SelectedItem);
form.Show();
form.Closed += Form_Closed;
}
private void newContractorBtn_Click(object sender, RoutedEventArgs e)
{
NewContractor form = new NewContractor();
form.Show();
form.Closed += Form_Closed;
}