function ShowCallbackBox(thispropref)
{
	//Add propref to form
	var parent = document.getElementById('enquiryform');
	var proprefHiddenInput = document.createElement('input');
	proprefHiddenInput.setAttribute("type", "hidden");
	proprefHiddenInput.setAttribute("name", "propref");
	proprefHiddenInput.setAttribute("value", thispropref);
	parent.appendChild(proprefHiddenInput);
	
	//get window width and height
	var myWidth = 0, myHeight = 0;
	if( typeof( window.innerWidth ) == 'number' ) {
		//Non-IE
		myWidth = window.innerWidth;
		myHeight = window.innerHeight; 
	} else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
		//IE 6+ in 'standards compliant mode'
		myWidth = document.documentElement.clientWidth;
		myHeight = document.documentElement.clientHeight;
	} else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
		//IE 4 compatible
		myWidth = document.body.clientWidth;
		myHeight = document.body.clientHeight;
	}       
	
	//Get current position in page of the top of the window 
	var has_inner = typeof(window.innerWidth) == 'number';  
	var has_element = document.documentElement && document.documentElement.clientWidth;  
	var windowTop = has_inner ? pageYOffset : has_element ? document.documentElement.scrollTop : document.body.scrollTop;
	
	//Set form width, height and visibility
	var boxwidth = parseInt(document.getElementById('floatdiv').style.width);
	var boxheight = parseInt(document.getElementById('floatdiv').style.height);
	document.getElementById('floatdiv').style.left=parseInt((myWidth-boxwidth)/2) + 'px';
	document.getElementById('floatdiv').style.top=(windowTop + parseInt((myHeight-boxheight)/2)) + 'px';
	document.getElementById('floatdiv').style.visibility='visible';
}