Group Invert and Feather, since they are in Effects category.

All options are be grouped into six categories:
1. layer name
2. layer types
3. basic settings (blend, opacity, brush size)
4. shapes (such as number of star points, angle, etc.)
5. effects (such as feather, invert)
6. advanced settings (such link origins, spline origins at center, etc.)

https://raw.github.com/jcome/synfig_ui/master/plain/ux/tooloptions-window.png