title: getBoundingClientRect() inconsistency
body: <p>I have an issue with DOMnode.getBoundingClientRect() because the data returned is not consistent. I am using <code>windows.onload</code> (for the lack of a better option) to trigger my function which takes a <code>getBoundingClientRect().height</code> of an element to do some calculation with it.</p>
  
  <p>Issue is, the height of the element is not always consistent. <code>window.onload</code> even should fire last in the page lifecycle as far as i know and both the content and the stylesheets and external resources should be loaded by then, however the page apparently still hasn't rendered it properly yet since I sometimes get height values of like 400, 528, 630 and sometimes its correct (700) for an element I am trying to read.</p>
  
  <p>Thoughts?</p>
  
  <p>Is there some other way to detect when the a <code>div</code> (or a page) has had itself rendered fully?</p>