Hide Unassigned Slots Re-appear

[Beherrit]

User Story:
As a user I would expect unassigned slots to remain hidden from the user as they move abilities around on the cross bars.

Actual:
When a user moves an ability to an unassigned slot that now unassigned slot will remain visible to the user. The user must re-select Hide unasigned slots.

Notes:
Is it possible to make it update when an ability has been moved/changed location?