To make a given component trigger a move of the animob you set the
ringtrigger bit of that animcomp's flags field. when the system software
encounters this flag, it adds the values of ringxtrans and ringytrans to
the anx and any values of the controlling animob.  the next time you
execute drawglist(), the drawing sequence will use the new position.

You usually set ringtrigger in only one of the animation components in a
sequence (the last one); however, you can use this flag and the
translation variables any way you wish.