Integrating bash into a GTK+ application

[Horror Vacui <horrorvacui gmx net>]

I'm writing a program that should display a bash window, and be able to 
read from and write to this window, without interfering much. I'm in 
process of learning programming, so I don't know what's the best way to 
achieve this. I could do it in some roundabout-way, but since I intend 
to write a useable program and not only something to learn on, I'd like 
to do it the right way.

A bit of description: I'm participating in a number of Linux-newbie 
lists, and a very common kind of question you get asked is "Tell me how 
to do this, but please without the command-line". The command line is 
great, but hard to learn, and many people could use help there. The idea 
is to write something like an xterm with an additional graphical UI, 
which should provide things like keyword search (so you can type "I want 
to move files" and get presented with a reasonable choice of related 
commands), organisation of available options in the most common and 
likely to be used, and specialised, with additional help and 
explanations. Actions in the GUI should immediately be visible in the 
bash window as they're selected, so people don't get locked into my 
GUI's way of doing it, but learn and come to a point where they don't 
need it any more. Therefore, it's important that the bash be a genuine 
bash, and not some kind of look-alike that'll behave in a non-standard 
way and teach people wrong lessons.

I already have a kind of one-quarter functional skeleton-draft of the 
GUI part, and don't think it's good to work further on that before I 
have at least one-quarter functional bash.

Thanks in advance.