title: How center modal dialog in scrolled window with position absolute?
body: <p>I'm trying to center a modal dialog in scrolled window. This modal are position absolute because must be draggable in screen. I use this plugin for draggable function:</p>
  
  <p><a href="http://threedubmedia.com/code/event/drag" rel="noreferrer">http://threedubmedia.com/code/event/drag</a></p>
  
  <p>My problem is that this modal has position absolute if I put top: 50% it display modal in center window but not considering all scrolled window.</p>