Span monitors?

[iscariot]

I'm in ubuntu linux and I'd like to span multiple monitors.  I've tried setting the numscreens value and that doesn't work.  I've also tried to set the per windows options to no avail.  What happens is that it runs full screen and stretches across my two monitors.  I'd really like to play Punch-Out with the upper screen on one monitor and the lower screen on the other.  How do I do this?

[Calamity]

Multiple monitors won't work with SDL 1.2 MAME (current). You need to compile it for SDL 2.0. Please report back if you succeed with this.