Thanks to @LotPings who pointed me to an other answer, I managed to create a VB script which regularly reads text from a file and displays it in the notification area (the 29 on the picture).

Currently it's only two characters, but you can use a smaller font to display more.
Note that I'm not a Windows programmer, nor a VB programmer, so the code is not pretty, I just copy pasted from examples until I made it work.
Here's the code which you can compile with vbc.exe (e.g. C:\Windows\Microsoft.NET\Framework64\v4.0.30319\vbc.exe
):
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Timers
Public NotInheritable Class Form1
Inherits System.Windows.Forms.Form
Private contextMenu1 As System.Windows.Forms.ContextMenu
Friend WithEvents menuItem1 As System.Windows.Forms.MenuItem
Friend WithEvents notifyIcon1 As System.Windows.Forms.NotifyIcon
Private components As System.ComponentModel.IContainer
Private fontToUse As System.Drawing.Font
Private brushToUse As System.Drawing.Brush
Private bitmapText As System.Drawing.Bitmap
Private g As System.Drawing.Graphics
Private hIcon As IntPtr
Private aTimer As System.Timers.Timer
<System.STAThread()> _
Public Shared Sub Main()
System.Windows.Forms.Application.Run(New Form1)
End Sub 'Main
Public Sub New()
Me.components = New System.ComponentModel.Container
Me.contextMenu1 = New System.Windows.Forms.ContextMenu
Me.menuItem1 = New System.Windows.Forms.MenuItem
' Initialize contextMenu1
Me.contextMenu1.MenuItems.AddRange(New System.Windows.Forms.MenuItem() _
{Me.menuItem1})
' Initialize menuItem1
Me.menuItem1.Index = 0
Me.menuItem1.Text = "E&xit"
' Set up how the form should be displayed.
Me.ClientSize = New System.Drawing.Size(292, 266)
Me.Text = "Notify Icon Example"
' Create the NotifyIcon.
Me.notifyIcon1 = New System.Windows.Forms.NotifyIcon(Me.components)
notifyIcon1.ContextMenu = Me.contextMenu1
aTimer = New System.Timers.Timer(300000)
AddHandler aTimer.Elapsed, AddressOf OnTimedEvent
aTimer.AutoReset = True
aTimer.Enabled = True
UpdateIcon
Me.WindowState = FormWindowState.Minimized
Me.ShowInTaskbar = False
End Sub 'New
Private Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
'Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
' e.SignalTime)
UpdateIcon
End Sub
Private Sub UpdateIcon
Dim fileReader As String
fileReader = My.Computer.FileSystem.ReadAllText("c:\temp.txt")
fontToUse = New Font("Microsoft Sans Serif", 16, FontStyle.Regular, GraphicsUnit.Pixel)
brushToUse = New SolidBrush(Color.White)
bitmapText = new Bitmap(16, 16)
g = Drawing.Graphics.FromImage(bitmapText)
g.Clear(Color.Transparent)
g.DrawString(fileReader, fontToUse, brushToUse, -4, -2)
hIcon = (bitmapText.GetHicon)
Me.notifyicon1.Icon = Drawing.Icon.FromHandle(hIcon)
notifyIcon1.Visible = True
End Sub
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
' Clean up any components being used.
If disposing Then
If (components IsNot Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub 'Dispose
Private Sub notifyIcon1_DoubleClick(Sender as object, e as EventArgs) handles notifyIcon1.DoubleClick
' Show the form when the user double clicks on the notify icon.
' Set the WindowState to normal if the form is minimized.
if (me.WindowState = FormWindowState.Minimized) then _
me.WindowState = FormWindowState.Normal
' Activate the form.
me.Activate()
end sub
Private Sub menuItem1_Click(Sender as object, e as EventArgs) handles menuItem1.Click
' Close the form, which closes the application.
me.Close()
end sub
End Class 'Form1