EntityFramework 6 Transaction.Rollback and Commit - winforms

Question

I have a requirement to make a Cancel Button that will rollback all changes since the last context save. I got it were the rollback worked on a button click. However, the DataGridView didn't reflect the change. If I quit the program I can see that no data was changed.
I got the following form to work ( I don't see any errors in the Output window ) however, everything I read says to wrap the context in a using statement. Does that still apply in this situation? I have used Rollback and commit in a save method try/catch but this plane ole' doesn't look right. What if I spawn to another Form, will it add to the current transaction or not?
/// <summary>
/// </summary>
public partial class Form2 : Form
{
/// <summary>
/// </summary>
private TestContext _context;
/// <summary>
/// </summary>
private DbContextTransaction _transaction;
/// <summary>
/// </summary>
public Form2()
{
InitializeComponent();
}
/// <summary>
/// </summary>
/// <param name="e"></param>
protected override void OnClosing(CancelEventArgs e)
{
base.OnClosing(e);
_transaction.Rollback();
_context.Dispose();
}
/// <summary>
/// </summary>
/// <param name="e"></param>
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
_context = new TestContext();
_transaction = _context.Database.BeginTransaction();
SetupDataGridView();
}
/// <summary>
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btnCancel_Click(object sender, EventArgs e)
{
_transaction.Rollback();
_context = new TestContext();
SetupDataGridView();
_transaction = _context.Database.BeginTransaction();
}
/// <summary>
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btnSave_Click(object sender, EventArgs e)
{
Validate();
PersonDataGridView.CommitEdit(DataGridViewDataErrorContexts.Commit);
_context.SaveChanges();
_transaction.Commit();
PersonBindingSource.ResetBindings(true);
_transaction = _context.Database.BeginTransaction();
}
/// <summary>
/// </summary>
private void SetupDataGridView()
{
_context.People.Load();
ObservableCollection<Person> people = _context.People.Local;
PersonBindingSource.DataSource = people.ToBindingList();
PersonBindingSource.RaiseListChangedEvents = true;
PersonDataGridView.AutoGenerateColumns = false;
PersonDataGridView.DataSource = PersonBindingSource;
}
}