I just came across this paragraph in the in-app help:
5.2 Dotted Button
The dotted note button increases the quantization raster by 50%. For example if the 1/8 note button and the dotted button are enabled, the quantization resolution is 1/6 of a bar.
I’d think that a dotted 1/8 note amounts to 3/16 of a bar, not 1/6, though the difference is small