Private Sub cancelAsyncButton_Click( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles cancelAsyncButton.Click

    ' Cancel the asynchronous operation.
    Me.backgroundWorker1.CancelAsync()

    ' Disable the Cancel button.
    cancelAsyncButton.Enabled = False

End Sub 'cancelAsyncButton_Click

private void cancelAsyncButton_Click(System.Object sender, 
    System.EventArgs e)
{   
    // Cancel the asynchronous operation.
    this.backgroundWorker1.CancelAsync();

    // Disable the Cancel button.
    cancelAsyncButton.Enabled = false;
}

void cancelAsyncButton_Click( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{  
   // Cancel the asynchronous operation.
   this->backgroundWorker1->CancelAsync();

   // Disable the Cancel button.
   cancelAsyncButton->Enabled = false;
}