title: How can I detect wallpaper changing as a result of the Windows 7 slideshow?
body: <p>I am writing a program that needs to know when the desktop wallpaper changes. After some searching, I found a partial solution:
  <a href="http://www.neowin.net/forum/topic/567779-net-detect-wallpaper-change/" rel="nofollow">http://www.neowin.net/forum/topic/567779-net-detect-wallpaper-change/</a></p>
  
  <p>Essentially, it says to listen for the <a href="http://msdn.microsoft.com/en-us/library/ms725497.aspx" rel="nofollow"><code>WM_SETTINGCHANGE</code> message</a>, and check the wallpaper. Unfortunately, this message does not appear to be sent when the wallpaper is changed as a result of the Windows 7 wallpaper slideshow. In fact, no message seems to be sent to my application at all for this (the only time I've ever seen <code>WndProc</code> <em>not</em> get constant messages :)).</p>
  
  <p>So my question is, short of polling the registry and wallpaper file for changes, is there a way to detect when this happens? Does anyone know where I can find API docs that list what function gets called?</p>