the design of filter is not done yet.
It would be good to have the possibility of have a layer visible but excluded to render on file or preview, just visible on work area (references layers for example).
References Layers type/status sounds like a great idea, I remember there were users required similar feature somewhere in forums. the above mockup updated!
In my work area, most of graphics editors have this functionality, one layer can be set to non-printed, it means in editor, those layers are exactly the same as other layers, but when you print your artwork, they will be ignored by printer/image Rip.
It means two parts will be involved to implement it, sif file, and the render.
This feature was implemented today -
github.com/blackwarthog/synfig/ … -rendering