title: How to deal with slow widgets rendering in Ext GWT (GXT)?
body: <p>I have window with few widgets inside. When it is rendered, it shows in top left corner for a second and then is centered.</p>
  
  <p>Is there any chance to lazy rendering? I mean that window is centered first and then child widgets are rendered.
  Or maybe I can hide window content behind mask during it is rendered?</p>