title: How to detect when the user switches to the Log On screen?
body: <p>I need to know when the user switches to the logon screen (as triggered by ctrl-alt-del) <a href="https://connect.microsoft.com/VisualStudio/feedback/details/602232/when-using-cachemode-bitmapcache-upon-waking-up-from-sleep-wpf-rendering-thread-consumes-40-cpu#tabs" rel="nofollow noreferrer">in order to circumvent a pesky bug in WPF</a>. I want to work around this bug by reinitializing my GUI after returning from the logon screen. Currently it works, but I have to trigger it manually.</p>
  
  <p>I have found <a href="https://stackoverflow.com/a/652574/590790">SystemEvents.SessionSwitch</a>, but unfortunately this is only triggered when logging off.</p>
  
  <p>How can I detect when the logon screen is displayed by forming ctrl-alt-del?</p>