function add_smile(s)
{
   document.comment_form.comment.value += ' *' + s + '*'; 
}

function showTab(tabId, tabNo)
{
var tabCollection = document.getElementById(tabId);
tabCollection.className='Tab'+tabNo+'Visible';
}

function go_from_select(url) 
{
if(url!=0) { document.location.href = 'http://www.hudebni-scena.cz' + url; }
}

function checkEmail(form)
{
	if(form.email.value.indexOf('@', 0) == -1)
		{
		alert("Tato emailová adresa je neplatná!");
		return (false);
		}

	if(form.email.value.indexOf('.', 0) == -1)
		{
		alert("Tato emailová adresa je neplatná!");
		return (false);
		}
	
	return (true);			

}