ok, a new version has been submitted for approval.

thanks to both @jcrennan and @simon1066 for pointing out the problem and the proposed fix.

hope you find the new version more useful. i did incorporate a small change so that one can see all products in sub-categories of a particular category. you can always select the sub-category to see only those products. sub-sub categories require selecting that category, or 1 level above. hopefully once approved, and you play with the changes you will see what i mean.

best.