[RMX] Tuner not changing in absolute units

On http://remix-tools.com/glyphsapp it states that the Tuner should adjust by absolute units, so I assume this means if I enter ‘40’ in height, it should change by +40?

Right now it’s something like ‘+37’ sometimes ‘+38’ in the case of ‘40’ ?

In the mean time I’m using the Scaler and % values, it’s working better for what I’m trying to do anyway (font wide editing).