gizmoControl by Martin Breidt is a macroscript that appears in the "MB Tools" category after you run the .mcr. It links the transformation of a modifier gizmo to another scene object, so the gizmo stays fully aligned to that object. That control object can be freely animated by any kind of controller and linked to any other scene node. In some ways it resembles World Space Modifiers, but it works for any kind of modifier gizmo.
The tool suits complex modifier animations: animating a Slice modifier's plane along a path, attaching a UVW Map modifier to an animated helper object, transforming a Displace modifier with another object, or letting an extra node control the symmetry plane of a Symmetry modifier.
Holding SHIFT on the Link button keeps the initial offset, so the gizmo stays where it is but follows further movement of the control node; holding SHIFT on Reset keeps the current gizmo transformation while removing the link. A button removes the scripted controller, and the script works with Merge and Xref links. It is compatible with 3ds Max 8 through 2022.