BIG UPDATE!
I've worked out some updates and a new visual editor for the gui system.
To use the gui just download http://pastebin.com/Dfgc6z0T to a computer as /lib/gui.lua and try your best.
If you don't want to fight with the placing of elements on the screen, then you want to use the visual editor.
It's alpha state, but i hope it will make no errors.
The editor will create a full lua code as frame work for your own program in resolution 80x25 like for a tier 2 screen. But you need a tier 3 screen to use the editor it self. The program you can run then on a ti