The MouseOverAny Sensor casts a ray from somewhere near the cameras origin to a far away point (100BU) both under the system mouse cursor.
The issue is that the MouseOverAny Sensor does not trigger the connected controller when hitting another object (see Collision sensor).
In a final game it is not likely that the mouse hits nothing as the whole view will be filled with objects.
Add a Pulse mode (as for the Collision Sensor).
This allow more efficient checks when the mouse is other a different game object.
Enable True Pulse and let Python check if the hitObject changed.
This is very inefficient and should not be done at each frame.
It shouldn’t be a big deal to implement this enhancement.