To orient the drop shadow where it belongs,use the Geometry->Mirror/Rotate
transform, and up-down flip the image from the previous page.

This is the mask we want to incorporate into the workflow, so save it somewhere.

The workflow will save another copy of the mask with the workflow, but you should save
your own copy just in case the workflow gets corrupted. Workflows will throw
masks away if you change some setting in the workflow so that it is presented with an image
that does not have the same dimensions as the mask.