title: Set position of window with AppleScript
body: <p>I'm trying to set the position of the Messages.app chat window using AppleScript.</p>
  
  <pre><code>tell application "System Events"
      set position of window 1 of application "Messages" to {100, 100}
  end tell
  </code></pre>
  
  <p>With this code I get an error:</p>
  
  <pre><code>error "Messages got an error: Can’t set «class posn» of window 1 to {100, 100}." 
  number -10006 from «class posn» of window 1
  </code></pre>
  
  <p>What does that mean?</p>
  
  <p>If I try the same code with Finder it works. But most of the other applications don't work.</p>