title: What data can a HID device receive?
body: <p>I am designing a USB keyboard with special capabilities. What information can such a HID device receive from the host?</p>
  
  <p>Can I via USB:</p>
  
  <ul>
  <li>Read data from a form on the screen?</li>
  <li>Find out what OS the user is on?</li>
  <li>Find out if there's been an error message?</li>
  <li>Even 'know' what's going on visually on the screen, i.e. what program is selected or whether the program is windowed or fullscreen?</li>
  </ul>
  
  <p>Thank you!</p>