title: Are there special considerations for a windows service to send messages to user windows?
body: <p>I have to write a Windows Service application (no GUI) that will monitor an event, and if it occurs will send a standard windows message to an application. The handle of the application will be given to the service by a DLL which is then unloaded, so a windows message is the way we wish to use.</p>
  
  <p>The question though is whether the service needs to do anything special to use SendMessage to the window handle, given that it might be on a different screen or something in Vista. Is this possible, and if so, what do I have to do please?</p>