If the layer shadow settings are changed the Undo does not undo the shadow change.

Steps to reproduce

1. Select the Stamp Tool and Place a Stamp with Layer shadow (Fantasy Battlemaps, Wooden Walls)

2. Select a Stamp with Layer Shadow with the Select Tool

3. Change the layer shadow settings

4. Press ctrl + z

Expected: The changed layer shadow settings would go back to what they were before when undo is used.

Actual: The shadow settings do not go back.