--- X Forwarding After su - ---

In .bashrc of main login add

### xauth list $DISPLAY
### echo $DISPLAY

echo "xauth add `xauth list $DISPLAY`"
echo " "
echo "export Display=`echo $DISPLAY`"

sudo -i or su -

Co and Paste the lines echoed above.

Something Like:

xauth add <hostname>.cc.binghamton.edu/unix:11  MIT-MAGIC-COOKIE-1  f81c9b88205747b13ee6fb32878ca997
 
export Display=localhost:11.0