title: Send combination of keystrokes to background window
body: <p>After a lot of research on Stackoverflow and google, it seems that it's difficult to send a combination of keystroke to a background window using it's handle. For example, I want to send CTRL + F. It seems that Sendmessage doesn't work, and sendinput isn't effective because the window needs the focus. </p>
  
  <p>So the my last thought is about hooking: is there anyway to use that way to send combination?</p>