We will start with a blank workflow, loaded with a sample image we will use to construct the template.

Midway through building the workflow, we will have to take a time-out and construct a mask
for the drop shadow, but for now we can use the workflow to get us to the point
where we need to reference the mask.

The first step ensures we start off with an image of known pixel dimensions
(or else a mask will not work). So insert the first operation into the workflow --
a resizing operation.