At the moment, you can see the total number of items in a list (for grid/multiselect grid) and even the number of items you have selected in that list (for multiselect grid).
It would be nice to also have these totals for both sides of a dual list. This makes it easier to work with dual lists that contain a lot of items.
==== Edit ====
This feature has been scoped into the following
  • Add the total number of items for the left and right side of a dual list
  • Keep the numbers up to date when moving items from left to right and the other way