function colsheight()
{
   var leftheight;
   var centerheight;
   var rightheight;

   leftheight   = document.getElementById("left").offsetHeight;
   centerheight = document.getElementById("center").offsetHeight;
   rightheight  = document.getElementById("right").offsetHeight;
   windowheight = getWindowHeight();
	
   var allheights  = new Array(leftheight, centerheight, rightheight, windowheight);

   function Numsort(a,b)
   {
     return b-a;
   }
   allheights.sort(Numsort);


   document.getElementById("left").style.height   = allheights[0] + 'px';
   document.getElementById("center").style.height = allheights[0] + 'px';
   document.getElementById("right").style.height  = allheights[0] + 'px';

}

function getWindowHeight(){
var x,y;
if (self.innerHeight) // all except Explorer
{
	x = self.innerWidth;
	y = self.innerHeight;
}
else if (document.documentElement && document.documentElement.clientHeight)
	// Explorer 6 Strict Mode
{
	x = document.documentElement.clientWidth;
	y = document.documentElement.clientHeight;
}
else if (document.body) // other Explorers
{
	x = document.body.clientWidth;
	y = document.body.clientHeight;
}

	return y;
}