Sometime is useful for other furniture with doors to see if you could open.

YES! I would love to add sashes to the opening drawers and doors of cabinets. Drawers showing a square sash, and cabinet doors the normal sashes as regular doors and windows have.
Implementation could be problematic if you add sashes for the ball deformation (a circle?). All the sashes around a mannequin can possibly be a little too much of a good thing. But for hinges and rails it's a no-brainer.