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, centerVertically, newHeight) {
	if (typeof window.innerWidth != 'undefined') {
		viewportheight = window.innerHeight;
	} else {
		viewportheight = document.documentElement.clientHeight;
	}
	if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
		blanket_height = viewportheight;
	} else {
		if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
			blanket_height = document.body.parentNode.clientHeight;
		} else {
			blanket_height = document.body.parentNode.scrollHeight;
		}
	}
	var blanket = document.getElementById('blanket');
	blanket.style.height = blanket_height + 'px';
	var popUpDiv = document.getElementById(popUpDivVar);
	if (centerVertically) {
	  popUpDiv_height = (blanket_height / 2) - (newHeight / 2); //the half popup's height
  	popUpDiv.style.top = popUpDiv_height + 'px';
	} else {
    popUpDiv.style.top = newHeight + 'px';
  }
}
function window_pos(popUpDivVar, newWidth) {
	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) - (newWidth / 2); //the half popup's width
	popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
	blanket_size(windowname, false, 390);
	window_pos(windowname, 600);
	toggle('blanket');
	toggle(windowname);		
}