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 ((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';
}

function loadImage(imgId, imgNumber) {
	var imgSrc = 'images/teaser_' + imgNumber + 'l.png';
	document.getElementById(imgId).src = imgSrc;
}

function popup(divId, imgId, imgNumber) {
	/*loadImage(imgId, imgNumber);*/
	blanket_size(divId);
	toggle('blanket');
	showdeadcenterdiv(divId, imgId);
	toggle(divId);
}

function showdeadcenterdiv(divid, imgId) {
	var Xwidth = document.getElementById(imgId).width;
	var Yheight = document.getElementById(imgId).height;
	// First, determine how much the visitor has scrolled
	Yheight = (Yheight > 600 ? 600 : Yheight); // image with or
	Xwidth = (Xwidth > 800 ? 800 : Xwidth); // image with or max-width

	var scrolledX, scrolledY;
	if (self.pageYOffset) {
		scrolledX = self.pageXOffset;
		scrolledY = self.pageYOffset;
	} else if (document.documentElement && document.documentElement.scrollTop) {
		scrolledX = document.documentElement.scrollLeft;
		scrolledY = document.documentElement.scrollTop;
	} else if (document.body) {
		scrolledX = document.body.scrollLeft;
		scrolledY = document.body.scrollTop;
	}

	// Next, determine the coordinates of the center of browser's window

	var centerX, centerY;
	if (self.innerHeight) {
		centerX = self.innerWidth;
		centerY = self.innerHeight;
	} else if (document.documentElement
			&& document.documentElement.clientHeight) {
		centerX = document.documentElement.clientWidth;
		centerY = document.documentElement.clientHeight;
	} else if (document.body) {
		centerX = document.body.clientWidth;
		centerY = document.body.clientHeight;
	}

	// Xwidth is the width of the div, Yheight is the height of the
	// div passed as arguments to the function:
	var leftOffset = scrolledX + (centerX - Xwidth) / 2 - 30;
	// assure that right corner is still visible on small screens for close
	leftOffset = (leftOffset < 0 ? leftOffset * 2 : leftOffset);

	// -30 for hspace, border and padding
	var topOffset = scrolledY + (centerY - Yheight) / 2;
	// assure that large images are still on screen
	topOffset = (topOffset < 0 ? 0 : topOffset);

	/*
	 * alert('Xwidth: ' + Xwidth + ' Yheight: ' + Yheight + ' scrolledX: ' +
	 * scrolledX + ' scrolledY: ' + scrolledY + ' centerX: ' + centerX + '
	 * centerY: ' + centerY);
	 */

	// The initial width and height of the div can be set in the
	// style sheet with display:none; divid is passed as an argument to // the
	// function
	var o = document.getElementById(divid);
	var r = o.style;
	r.position = 'absolute';
	r.top = topOffset + 'px';
	r.left = leftOffset + 'px';
}