Actually, I suspect his computer is already set to that, that's how come he used not to have the bars. GOG did change the way they set up DOSBox recently. They used to have "fullresolution" set to "original" so people's video cards/monitors did the scaling. Now they've configured DOSBox to scale to the user's desktop resolution. This is superior, however since DOSBox auto-pillarboxes and maintains aspect ratio by itself, people who prefer stretchy fat-o-vision get screwed over.

Ah, that would make sense. I think I'll just leave walking OP through the steps to reconfigure DOSBox to you.

its kinda making me mad because all of the desktops i play on its all messed up because of the mac thing.
ok, it worked! you had the solution!

This is actually technically speaking an improvement as it was configured wrong before, but I understand that you prefer it to be full screen at the cost of things not being the right shape. I think to call it messed up and unplayable is a bit of an overstatement though. :P

Did you give the instructions on how to "fix it" a go?

EDIT:

Phew, I'm glad we got there eventually. :)

i know right! it was just on and on and on.