Hi John,
My preferred way of making drop shadows is to use a cutout but that requires it being added to each image in the editor.
See 1st attached image
but it seems to me that IF it were possible to use the Photo Matt feature with a negative number on the top and left, and a positive number on the bottom and right it would simplify the task hugely with no need for template creation.
It can be done at present as follows.
Add a matt with zero values on the appropriate sides, see 2nd & 3rd screen shots below.
In the Page editor, select the IMAGE or Template and us the arrow keys to move the image relative to the matt; you could use the size/position tab to set exact dimensions.
NB. you must select & move the image or template and not the matt as that will move both matt and image/template together.
See 4th screen shot below.
Terry