You can't change the relative resolution, it's just the way it works. This allows to easily play hi-res games at a lower resolution.
AFAIK:
There are plans to support a more accurate positioning system though:
http://www.adventuregamestudio.co.uk/tracker.php?action=detail&id=434
AFAIK:
Resolution | Relative resolution |
320x200 | 320x200 |
320x240 | 320x240 |
640x400 | 320x200 |
640x480 | 320x240 |
800x600 | 400x300 |
There are plans to support a more accurate positioning system though:
http://www.adventuregamestudio.co.uk/tracker.php?action=detail&id=434