title: Posting a message to a GUI thread while affecting the result of GetKeyState
body: <p>I know that the <code>GetKeyState</code> method, when called from a GUI thread while processing a message retrieved by <code>GetMessage</code>, examines the thread's message queue to determine the state of a given key at the time the message was put in the queue.</p>
  <p>My question is - is it possible to affect that value in runtime?
  I'd want to be able to post a <code>WM_KEYDOWN</code> message to a Window, while tweaking the added message such that the receiving thread would think that the CTRL key is pressed. To be clear - I don't want to actually press CTRL - I want only the receiving thread to think that CTRL was pressed.</p>
  <p>Is it possible?</p>