function clearField(obj){
			if (obj.defaultValue==obj.value) obj.value = '';}
			
			function clearPasswordField(obj){
			if (obj.defaultValue==obj.value) obj.value = '';}
			
			function restoreUsernameField(obj){
			if (obj.value=='') obj.value = 'username';}
			
			function restorePassField(obj){
			if (obj.value=='') obj.value = 'password';}