JAL-3446 Dynamic menu - Moves calc sortby tree item creation to opening

JAL-3446 Dynamic menu - Moves calc sortby tree item creation to opening
of its submenu, rather than the upper-level sort menu.

- suggestion only; changes setVisible to setEnabled, more along the
lines of standard practice (?)
- allows for a simple change from "enabled" to "visible" if desired, but
still leaves the submenu creation in its most proximate location.