function switchImage(gallery, newImage, index) {
	var largeImageDiv = document.getElementById('galleryLargeImage');
	largeImageDiv.src = '';
	largeImageDiv.src = 'templates/images/galleries/' + gallery + '/' + newImage;

	// make the old overlay a little bit transparent
	var oldOverlay = document.getElementById('gallery_img_' + currentDisplayImage);
	if (oldOverlay) {
		oldOverlay.className = "aLittleBitTransparent";
	}

	// and remove it from the current overlay
	var overlayDings = document.getElementById('gallery_img_' + index);
	if (overlayDings) {
		overlayDings.className="";
	}

	currentDisplayImage = index;
}