The operator stored when registering the asset shelf will be called with properties that reference the asset (a weak reference, split into three properties already used in other asset-related operators). The operator is called whenever a grid view item is activated, and is meant to do things like import and activate a brush asset. Previously Reviewed: https://projects.blender.org/blender/blender/pulls/117861 Pull Request: https://projects.blender.org/blender/blender/pulls/121402