Paths with stroke thickness
Fonts don't support paths with stroke thickness, only fill. But, we could allow you to specify a path with stroke thickness, then when exporting a font, that path's stroke could be outlined to create a filled shape.
Марсель Ишимбаев commented
As I get it, you mean "borders" of a shape, the path, and the feature being ability to work with it only and without black fill effect. If I am right, then this is great an idea. So many problems with lining shapes up will dissappear. Also would be great to on/off the feature. Sorry for breaking language.