var topZIndex = 5;

function focusimage(imageid) {
	//put the selected image on top;
	var image = document.getElementById(imageid);
	image.style.zIndex = topZIndex;
	topZIndex++;
	return true;
}

function getElementsByClassName(classname) {
    var a = [];
    var re = new RegExp('\\b' + classname + '\\b');
    var els = document.getElementsByTagName("*");
    for(var i=0,j=els.length; i<j; i++)
        if(re.test(els[i].className))a.push(els[i]);
    return a;
}

function displayImages(tags) {
	for(var i=0;i<tags.length;i++) {
		tags[i].className += ' show';
	}
}