[Aly El-Haddad]

كود :

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Control.CheckForIllegalCrossThreadCalls = False
        BackgroundWorker1.RunWorkerAsync()
    End Sub

    Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        If ListBox1.SelectedIndex < ListBox1.Items.Count - 1 Then
            TextBox1.Text = ListBox1.SelectedItem.ToString
            Dim myclass As New vt
            myclass.GetData(TextBox1.Text)
        Else
            ListBox1.SelectedIndex = -1
        End If
    End Sub
End Class