// show_element():
// Element ein und ausblenden, entweder getriggert (val = null) oder per value 0 oder 1

function show_element(id, val, mode){
	if(document.getElementById(id) != null){
		var el = document.getElementById(id);
		var returner = 0;
		if(val != null){
			if(val == '1'){
				el.style.display = 'block';
			} else {
				el.style.display = 'none';
			}
		} else {
			if (el.style.display == 'block') {
				el.style.display = 'none';
				returner = -1;
			} else {
				el.style.display = 'block';
				returner = 1;
			}
		}
	} else {
		alert('Nicht gefunden: ' + id);
	}
	
	if(mode == '1'){
		return returner;
	}
}