Possible to adjust the aspect ratio in Groovy Arcade?

[Silntdoogood]

Hey all,
I started this project two years ago, some things came up and it's sat for a while. The last week I've found some time and made some major progress. I'm using a 4:3 15khz monitor with an adjusted graphic card. Most games run fine, but vertical games have a bad vertical scrolling issue. A few scroll, but not as bad. I think they may be 1:1, or something close to 4:3.

 

The in game menu under [tab]->display doesn't do anything. The first two entries in the menu are "4:3" and "1:1 pixel scaling" but I can't seem to change them.

Does any one have any experience with 2012's Groovy Arcade's MAME UI?