function getCaptcha(imgobj) {
	if(imgobj.src.indexOf('code')>=0) return;
	var rnd = '';
	var chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
	for(idx = 0; idx < 4; idx++) rnd += chars.charAt(Math.round(Math.random()*chars.length));
	imgobj.src = 'captcha.php?code=' + rnd;
	document.getElementById('code').value = rnd;
}