function open_window(url, fenstername, breite, hoehe) {
	var features = 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=no';
	features = features + ',width=' + breite + ',height=' + hoehe;
	var mywindow = window.open(url, fenstername, features);
	var startx = (screen.width / 2) - (breite / 2);
	var starty = (screen.height / 2) - (hoehe / 2);
	mywindow.moveTo(startx, starty);
}

function show_image(image) {
	open_window(image, 'Preview', 640, 470);
}

function card_text(obj) {
	if (obj.value == "Hier klicken!") {
		obj.value = "";
	}
}