Use acme to switch between “slides” (actually just text files) in a directory. Blatantly stolen from Russ Cox (http://research.swtch.com/acme).

Slide

#!/usr/local/plan9/bin/rc
. /usr/local/plan9/lib/acme.rc
winname `{pwd}^/$1
winctl clean
winctl get

Slide+

#!/usr/local/plan9/bin/rc
current=`{basename $%}
currentx=`{9 grep -n '^'$current'([ 	]|$)' index | sed 's/:.*//'}
pagex=`{echo $currentx + 1 | hoc}
page=`{sed -n $pagex^p index | awk '{print $1}'}
if(~ $#page 0){
	echo no such page
	exit 0
}

Slide $page

Slide-

#!/usr/local/plan9/bin/rc
current=`{basename $%}
currentx=`{9 grep -n '^'$current'([ 	]|$)' index | sed 's/:.*//'}
pagex=`{echo $currentx - 1 | hoc}
page=`{sed -n $pagex^p index | awk '{print $1}'}

if(~ $#page 0) {
	echo no such page
	exit 0
}

Slide $page