title: Getting `xprop` of child/client window given X ID of frame
body: <p>I'd like to run the command <code>xprop -id [window_id]</code>.</p>
  
  <p>However, assume that for some odd reason, I only have access to the <code>window_id</code> of the <strong>frame</strong> for the window I'm after(i.e. the window manager's frame for the window as opposed to the window itself).</p>
  
  <p>How can I tell <code>xprop</code> that the <code>-id</code> is for the frame not the client window, and that I want the client window? Sort of the inverse to <code>xprop -frame</code> which will grab the information for the window you click on's <em>frame</em> as opposed to the window.</p>
  
  <p>Am I stuck with somehow parsing <code>xwininfo -children [frame_id]</code> to extract the child window id to pass that into <code>xprop</code>?</p>