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.
Rob Hutchings commented
Doh! Just spotted this after commenting on the handwriting suggestions. Definitely support this especially if you had a way to adjust/generate the stroke width profile, akin to the way you can adjust brushes in Illustrator et al.
Jeremy W. Sherman commented
It seems like this would be much easier to work with and tweak for hobbyist use. Finely tweaking the shape of a glyph is fine when I'm trying to make an amazing font, but for getting a script off the ground, I just want to draw some lines and curves and run with it with a simple stroke.
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.