Imports System.Windows.Threading
Imports System.IO


Public Class UserControl1
    Private WithEvents m_Timer As New DispatcherTimer

    Private Sub UserControl1_LayoutUpdated(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.LayoutUpdated
        If m_Timer IsNot Nothing Then
            m_Timer.Interval = TimeSpan.FromMilliseconds(3000)
            m_Timer.Start()
        End If
    End Sub


    Private Sub m_Timer_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles m_Timer.Tick

        InitializeComponent()

        Try
            

            Using sr As New StreamReader( "r:/regia/OnAir.txt")
                Dim line As String
                line = sr.ReadToEnd()

                TextBlock1.Text = line
            End Using
        Catch
            TextBlock1.Text = "Could not read the file"
        End Try



    End Sub

End Class

<UserControl x:Class="UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" Width="1920" Height="1080" xmlns:my="clr-namespace:vMixTitleLibrary;assembly=vMixTitleLibrary" Padding="5" Margin="5">

   

    
    <Grid  >
        <TextBlock Height="79" Margin="73,926,772,0" Name="TextBlock1" Text="TextBlock" VerticalAlignment="Top" Foreground="White" FontSize="56" Background="#FF145BAD" />
    </Grid>

</UserControl>