function setEmpty (source, default_value)
{
	var is_default_value = false;
	
	if (typeof default_value == "undefined")
	{
		switch (source.name)
		{
			case "from":
				is_default_value = source.value == "name";
				break;
			case "email":
				is_default_value = source.value == "e-mail" || source.value == "e-mail (required)";
				break;
			case "msg":
				is_default_value = source.value == "your message" || source.value == "tell us something!";
				break;
		}
	}
	else
	{
		is_default_value = source.value == default_value;
	}
	
	if (is_default_value)
		source.value = "";
}

function setText (source, default_value)
{
	var value;
	
	if (typeof default_value == "undefined")
	{
		switch (source.name)
		{
			case "from":
				value = "name";
				break;
			case "email":
				value = "e-mail";
				break;
			case "msg":
				value = "your message";
				break;
		}
	}
	else
	{
		value = default_value;
	}
		
	//TODO: check for emptyness
	if (trim(source.value) == "")
		source.value = value;
}

function maxLenght (source, max)
{
	if (source.value.length > max)
	{
		source.value = source.value.substr(0, max);
	}
}

function trim (string)
{
	return string.replace(/^\s+/, '').replace(/\s+$/, '');
}