Q: how to allow permanently other users to X

[Sándor Bárány]

My problem is the following: if I started kdm as user X and change to
user Y I have to use xhost + to be able to start xclock. (xhost
+localhost and the like is not enough.) But anyhow, I want to allow it
for the all users on the same machine permanently. I tried to put
localhost into /etc/kde2/kdm/Xaccess, /etc/X11/X0.hosts to no avail.