Mention you need to install dialog

[xeoncross]

sudo apt-get install dialog

In the initial check

if [[ ! $(type -P dialog) ]]; then
    echo -e "\e[1;31mI'm sorry, Dave. I'm afraid I can't do that.\e[0m" && exit 1
else
    sleep 3
fi

[alixaxel]

I don't remember why I added that check, but I know I had a reason for not installing dialog right away.

I think it had something to do with incompatibilities regarding the previous OSes (and their versions) halBox supported (Debian and Ubuntu), since the current version of halBox only works on Ubuntu 14.04 and it has dialog installed by default, I don't think there's a problem. If you want to fork and add support for other OS releases, you could create a specific script in packages/OS/Codename.sh to make it work.