I would like to know how to get an elements relative position to the document

With jquery I get 650 for the clientHeight and 680 for the footer, so this way I know it is no longer in the browsers view.

How do I get the 680 value with ext?

I tryd several

c = Ext.getBody();
   s = c.getScroll(); 
    top  = foot.getTop();
   pos = foot.getOffsetsTo(c);
    console.log("ext pos is "+pos+" en top is "+top+" en scroll is "+s.top);
I think I need a callback on the reload function to get the accurate height off the grid, but I dont yet know how to do that.

thanks, Richard