Cleanstretch with fixed resolution?

[cools]

Since MAME mainline doesn't have "cleanstretch 2" available I'm trying to use GroovyMAME for a specific setup where the image is scaled up the image in a controlled manner (integer on the vertical is critical, on the horizontal it's not so important), then applying an effect to drop scanlines over the top.

For testing I'm using no .ini files other than a game specific one - tnzs.ini:

monitor lcd
resolution 1600x900@60
aspect 16:9
cleanstretch 2

(cleanstretch 1 also doesn't work, neither does changing the monitor type)

Removing the cleanstretch line fixes the aspect ratio, but with cleanstretch added Groovy just fills the screen and the aspect ratio is gone.

Is there some combination of settings I'm missing? I want to use a fixed resolution and have the image cleanstretched

[Calamity]

Yes, I've confirmed this, there's no fix I could find but modifying the horizontal stretching from the slider control.

[cools]

Phew, I'm not going crazy.

(I'm aiming to eliminate the use of scanline generators in MAME/MESS setups, pretty sure if it worked as I'm thinking there'd be no need for them)

[rCadeGaming]

EDIT: sorry, accidental post.