function toggle(div_id) {
	var el = document.getElementById(div_id);
	if ( el.style.display == 'none' ) {	el.style.display = 'block';}
	else {el.style.display = 'none';}
}

function blanket_size(popUpDivVar) {
if (typeof window.innerWidth != 'undefined') {
viewportheight = window.innerHeight;
} else {
viewportheight = document.documentElement.clientHeight;
}

if(document.body.scrollTop > 0){
// For IE 5.5
bdy_ref = document.body;
}else{
bdy_ref = document.body.parentNode;
}

if ((viewportheight > bdy_ref.scrollHeight) && (viewportheight > bdy_ref.clientHeight)) {
blanket_height = viewportheight;
} else {
if (bdy_ref.clientHeight > bdy_ref.scrollHeight) {
blanket_height = bdy_ref.clientHeight;
} else {
blanket_height = bdy_ref.scrollHeight;
}
}
var blanket = document.getElementById('blanket');
blanket.style.height = blanket_height + 'px';
var popUpDiv = document.getElementById(popUpDivVar);
popUpDiv_height = screen.availHeight/2-350;//350 is the popup's height
popUpDiv.style.top = (popUpDiv_height + bdy_ref.scrollTop) + 'px';

}

function window_pos(popUpDivVar) {
	if (typeof window.innerWidth != 'undefined') {
		viewportwidth = window.innerHeight;
	} else {
		viewportwidth = document.documentElement.clientHeight;
	}
	if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
		window_width = viewportwidth;
	} else {
		if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
			window_width = document.body.parentNode.clientWidth;
		} else {
			window_width = document.body.parentNode.scrollWidth;
		}
	}
	var popUpDiv = document.getElementById(popUpDivVar);
	window_width=window_width/2-300;//150 is half popup's width
	popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
	blanket_size(windowname);
	window_pos(windowname);
	toggle('blanket');
	toggle(windowname);		
}