title: Capturing Key Press Event in my WPF Application which do not have focus
body: <p>I have developed an On Screen Keyboard in WPF. I need to capture the key
  press event (via Key Board) in order to keep a track of Caps Lock, Shift
  etc (whether they are pressed).
  Please note that my application loses focus when any other application
  (say notepad) is opened.</p>
  
  <p>Could anyone suggest how to achieve this in WPF?
  in short, my WPF application needs to capture the key press events even
  though it does not have focus. Kindly help.</p>