Thanks :)

I'm not sure whether to add the special_flags argument to DirtyLayered as DirtyLayered already partially handles this with the blendmode attribute on the DirtySprite objects.

In my humble opinion, it would make sense for the DirtyLayered to support this, since it is a subclass. Probably all the subclasses that come with pygame should support it?

Looks like the file needs formatting with the black formatter.

python3 -m pip install black --userpython3 -m black src_py

There’s a type issue here:
https://github.com/pygame/pygame/actions/runs/4218255639/jobs/7323102489

cd buildconfig/stubspython3 -m pip install mypy --userpython3 -m mypy.stubtest pygame --allowlist mypy_allow_list.txt

pygame/sprite.pyi:208: error: Argument 2 of "draw" is incompatible with supertype "AbstractGroup"; supertype defines the argument type as "int"  [override][20](https://github.com/pygame/pygame/actions/runs/4218255639/jobs/7323102489#step:6:21)pygame/sprite.pyi:208: note: This violates the Liskov substitution principle[21](https://github.com/pygame/pygame/actions/runs/4218255639/jobs/7323102489#step:6:22)pygame/sprite.pyi:208: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides

The problem is thatAbstractGroup (and most other groups) have the draw method being

defdraw(self,surface:Surface,special_flags:int=0)->List[Rect]: ...

butLayeredDirty has the draw method being

defdraw(self,surface:Surface,bgd:Optional[Surface]=None,special_flags:int=0)->List[Rect]: ...

so code that takes any instance ofAbstractGroup and passes thespecial_flags as the 2nd argument would actually be passing it as thebgd argument if that instance turned out to be aLayeredDirty.

I can thing of 2 solutions:

1. Make thespecial_flags argument keyword-only so that it can't accidentally be passed as thebgd argument toLayeredDirty
2. Add an unused argument to the other draw methods so thatspecial_flags is always the 3rd argument.

2. Add an unused argument to the other draw methods so that special_flags is always the 3rd argument.

I'm a fan of your second solution (except rename bgd tobackground orbgsurf). Because then there is a consistency with each of the classes draw methods.

Do you see any drawbacks with this solution 2?

(I couldn't find any code using a bgd keyword argument, so I think it's safe to rename)

Q: Is a blendmode(special_flags) attribute on sprite would be better here? IMHO, No. I think there's a use case where we want the special_flags to be used for the whole group. It's more convenient when you want everything to use the same

I agree that special_flags should be used for the whole group. Because then it will be consistent with all the other groups as the special_flags argument will always apply to everything in the group (and that won't depend on if its a normalGroup or aLayeredDirty)

Looks like there's a couple of pylint issues:

************* Module src_py.spritesrc_py/sprite.py:539:28: W0613: Unused argument 'bgsurf' (unused-argument)src_py/sprite.py:1169:16: W0612: Unused variable 'flags' (unused-variable)