title: value returned by cv.keywait() is not the character code
body: <p>i am using opencv with python binding</p>
  
  <p>want to get the value of the key pressed with the following code</p>
  
  <pre><code>    cv.waitkey(10)
  </code></pre>
  
  <p>it gives -1 when no key is hit and this value if any of the key is hit.</p>
  
  <pre><code>   -1
     -1
     -1
     536870939
     -1 
     -1
  </code></pre>
  
  <p>Could anyone  help me in this please.</p>
  
  <p>Thanks a lot</p>