WPF VB.Net

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="WPF" Width="240" Height="140" >
    
        Start
        
    


//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