This article discusses how to surround an entire sub-menu (not per-item) with a border or other styling.
Tigra stated that "We are working on special version of the Tigra Menu with table formatting of the menu blocks. With this version block borders will be much natural" however this doesn't appear to be available in the base product.
Is this going to be released or is it available in the PRO or GOLD products?
It's available in Tigra Menu GOLD