Grease Pencil - Add Texture Paint Mode

Grease pencil curves are allowed to use textures as their fill type. If possible, it would be amazing to be able to texture paint onto the "polygons" of a grease pencil line. That would bring grease pencil closer to emulating an actual raster art image editor.

I know there are setbacks because the texture fill is fairly buggy at the moment, but I still think it's something to strive for.

Setbacks I expect:

• Would require UV support for grease pencil
• Otherwise the current implementation of textures would need to be more robust
• may be difficult to translate from polygons to gp