function hideshow(num) {
        if (!document.getElementById('tree_'+num).style.display) document.getElementById('tree_'+num).style.display='none';
	if (document.getElementById('tree_'+num).style.display=='none') {
		document.getElementById('tree_'+num).style.display = 'block';
	} else {
		document.getElementById('tree_'+num).style.display = 'none';
	}
	return false;
}