title: mss sct.grab won't let me select which monitor to use
body: <p>I have two monitors connected to my computer with both active at the same time.  The monitors are not mirrored - each displays different content.</p>
  
  <p>I need to be able to select in code which of these two monitors I want to use with sct.grab.  </p>
  
  <p>I have seen and tested this code:  sct_img = sct.grab(sct.monitors[1])
  It works - I can change the "1" to "2" and it will indeed screenshot the other monitor - all of it.  However, I can't figure out how to pass into sct.grab both the parameters for the monitor I wish to use, AND the region of screen I wish to grab for just a partial screenshot.  It seems I can either get a partial screenshot, but not choose the monitor, or I can choose the monitor, but only get the full screen.  I need to choose the monitor, and also choose the region.  I'm looking for help with the appropriate syntax.</p>
  
  <p>I have this code: </p>
  
  <pre><code>sct_img = sct.grab({'top': 160, 'left': 160, 'width': 160, 'height': 135})
  </code></pre>
  
  <p>but what I want is somewhere to tell sct.grab which of my two monitors to get this from:  For example, something like a parameter in the dictionary specifying which monitor to use would be nice:</p>
  
  <pre><code>sct_img = sct.grab({'mon': 2, 'top': 160, 'left': 160, 'width': 160, 'height': 135})
  </code></pre>
  
  <p>Any help would be apprecitated.</p>