function prihlaseni(url) {
	var w=350;
	var h=280;
	var windowfeatures='toolbar=no, scrollbars=no, resizable=no, menubar=no';
	var winl = (screen.width - w) / 2;
	var wint = (screen.height - h) / 2;
	winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl;
	win = window.open(url, "prihlaseni", winprops+windowfeatures)
	if(parseInt(navigator.appVersion) >= 4){
		win.window.focus();
	}
}