Reset Active Operator

Question

I want to write a Handler that runs code only when the user stops translating an object, using bpy.ops.transform.translate (the 'G' key). So while the user is sliding the mouse around, nothing should happen besides the object being translated. But when they exit the modal operator (by left-clicking or pressing 'enter'), my code should run.

My approach:

@bpy.app.handlers.persistent
def detect_change(scene):
    op = bpy.context.active_operator
    opname = op.bl_idname.replace("_OT_", ".").lower() if op else ''

    # On entering translate mode, start checking for exit
    if opname == "transform.translate":
        waiting = True # This will be some sort of persistent variable.
        return

    # If not in translate mode, then run code
    elif waiting:
        my_function()
        waiting = False

# Add the handler
bpy.app.handlers.scene_update_post.append(detect_change)

The only problem is that after exiting the translate modal operator, the active_operator remains at transform.translate. It doesn't switch until another operator is called.

Any way to either force the operator to update to None or to detect exiting the modal operator?