i am guessing that it is a DosBox wrapper, to make management and running of games, both easier and prettier. :) No more mounting and all that crap.
Boxer should at least acknowledge DoxBox on their homepage IMO, feels to me a bit like taking DosBox's glory for themselves?
DOSBox is mentioned in the About window, the credits, and Boxer itself when you launch a gamebox. It also used to be on the website, though checking now I'm not sure where it's gone.
Boxer is properly GPL and you can find the source code here:
You're right - Boxer's homepage did actually acknowledge DOSBox until a couple of days ago, when I rewrote most of the copy and in the process took it out. I now realise this was caddish of me, and have added the acknowledgement back in.
It wasn't my intention to take credit for DOSBox's work; it’s an excellent emulator and responsible for 90% of what Boxer does. However, it's also extremely painful to use on the Mac - and I wanted to avoid the suggestion that Boxer's user experience was like that of DOSBox’s.
As airolson noted, DOSBox is also prominently credited within Boxer itself.