title: VB.NET BalloonTip from different threads
body: <p>My application runs a GUI thread and a timer-induced worker thread (the worker thread is created implicitly by the <code>Elapsed</code> method of the timer). </p>
  
  <p>Some messages are displayed via a BallonTip and the the problem is that tray icons evoked by the BalloonTips do not disappear. I noticed that the number of copies on my icon in the tray is linked to the number of threads that show BallonTip. My code is </p>
  
  <pre><code>Public Sub showPopup(xStrMessage As String)
          Me.notifyIcon.Visible = True
          Me.notifyIcon.ShowBalloonTip(1000, "VdtServer", xStrMessage, ToolTipIcon.Info)
  End Sub
  </code></pre>
  
  <p>How can I solve this? I would naturally like to have a single icon in the tray. Any help is much appreciated. </p>