//File:Window.xaml.vb Imports System Imports System.Windows Imports System.ComponentModel Namespace WpfApplication1 Public Partial Class Window1 Inherits Window Private worker As New BackgroundWorker() Private from As Long = 1 Private [to] As Long = 200 Private biggestPrime As Long Public Sub New() MyBase.New() InitializeComponent() AddHandler worker.DoWork, New DoWorkEventHandler(AddressOf worker_DoWork) AddHandler worker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf worker_RunWorkerCompleted) End Sub Private Sub Start_Click(sender As Object, e As RoutedEventArgs) worker.RunWorkerAsync() btnStart.IsEnabled = False txtBiggestPrime.Text = String.Empty End Sub Private Sub worker_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs) btnStart.IsEnabled = True txtBiggestPrime.Text = biggestPrime.ToString() End Sub Private Sub worker_DoWork(sender As Object, e As DoWorkEventArgs) For current As Long = from To [to] biggestPrime = current Next End Sub End Class End Namespace