Something

#!/bin/bash

cd /home/dive/changelog || exit 1

rm -f OldLog.txt
mv ChangeLog.txt OldLog.txt 2>/dev/null

/usr/bin/wget -N http://slackware.osuosl.org/slackware-12.2/ChangeLog.txt
/usr/bin/diff -n OldLog.txt ChangeLog.txt | sed '1d' > diff

[[ $(cat diff) == "" ]] && exit 0

let wc=$(wc -l diff | awk '{print $1}')

killall -q root-tail
export DISPLAY=:0.0
/usr/bin/root-tail -g 500x$[wc*12]+0+0 -font 6x12 --wordwrap --frame --color gray \
/home/dive/changelog/diff 2>/dev/null