function check_mail_form() {
	form = document.contact_us;
	if(form.name.value == "") {
		alert('You have to insert name!');
		form.name.focus();
		return false;
	}
	if(form.tel.value == "") {
		alert('You have to insert phone number!');
		form.tel.focus();
		return false;
	}
	if(form.email.value == "") {
		alert('You have to insert email!');
		form.email.focus();
		return false;
	}
	if(form.message.value == "") {
		alert('You have to insert questions/commnets!');
		form.message.focus();
		return false;
	}
}

function popUp(URL, width, height) {
	day = new Date();
	id = day.getTime();
	if(width >= 640) {
		width = 640;
	}
	if(height >= 480) {
		height = 480;
	}
	eval("page" + id + " = window.open('includes/show_image.php?image=../"+URL+"&width="+width+"', '" + id + "', 'toolbar=0, scrollbars=yes, location=0, statusbar=0, menubar=0, resizable=0, width=" + (width+40) + ", height=" + (height+40) + "');");
}