getStyle compatibility

getStyle

/* It is not possible to get certain styles set in css such as display using 
the normal javascript.  So we have to use this function taken from:
http://www.quirksmode.org/dom/getstyles.html */
function getStyle(el,styleProp)
{
   var x = document.getElementById(el);
   if (x.currentStyle) // IE
      var y = x.currentStyle[styleProp];
   else if (window.getComputedStyle)  // FF

      var y = document.defaultView.getComputedStyle(x,null).getPropertyValue(styleProp);
   return y;
}