Packages zenity and xterm must be installed for the script.
The script (UPDATE)
#!/bin/sh
zenity --question --text "Would you like to check updates?"
if [ $? = 0 ];
then
xterm -e su -c 'xterm -e slapt-get --update' root
else exit 0
fi
zenity --question --text "Would you like to install updates?"
if [ $? = 0 ];
then
xterm -e su -c 'xterm -e slapt-get --upgrade' root && zenity --info --text "System Upgraded"
fi
exit 1
The script must be executable (chmod +x UPDATE)
About using Slapt-get: https://www.slackwiki.com/Upgrade_Using_Slapt-get