Calling this state "active" has been confusing for a long time for a number of reasons:
- It's not clear that this is essentially a mouse hover state.
- Easy to confuse with "select" state (`UI_SELECT`), both terms are vague.
- Buttons can be "inactive" (`UI_BUT_INACTIVE`) which is totally related to this "active" state.
- Button handling can consider a button as active that doesn't have this flag set (e.g. during text input).
- Active and selected are well established terms in Blender, but they mean a different thing there.
See #112160.
Pull Request: https://projects.blender.org/blender/blender/pulls/114113