This patch implements the list panel system D7490 for grease pencil modifiers. It also moves their drawing to a callback in GpencilModifierTypeInfo in line with the extensible architecture refactoring goal T75724.
I also added the "set_error" function for grease pencil modifiers, which hadn't been added from mesh modifiers yet.
The implementation is exactly the same as for the modifier patch.
| Old | New |


































