xwindow Display and sudo

I am fairly new to SuSE and have recently switched from redhat and was wondering if someone could direct me to the correct sources of documentation. In redhat when I ran the command "sudo su -" the display variable was set properly and the root user was able to use the display. Under suse 9 I have to run xhost +localhost;sudo su - and then export the display. Does anyone know how to change this behavior or what documentation I need to read to understand why this is different. Thanks, chad