Normal node not automatically updating

Hi
I’ve done a test adding a driver to a Normal node into a Material. The Normal angle/vector is controlled by an empty object.
The “thing” works, if I render I can see that rotating the empty results into rotating the normal node.
However I see no change at all in the 3D viewport while I’m rotating the empty.
Is there a way to force the updating of this? Is this OK? Is a bug?
Here the test:
http://www.pasteall.org/blend/19030

Thanks

I’m going to take a wild guess and say that the node doesn’t get updated because the empty is a totally separate object and doesn’t force an update on the object the node tree is attached to.

Could be a bug or could be a limitation of the depsgraph.

Thanks. I see…
Maybe I could workaround that behavior with a script that, whenever I rotate the empty, it updates the material. Could it be done?