Bug 5878: Time Agg Series Slot unit column label incorrect after config change, until slot re-opened.
Bug Number: 5878
Release notes (y/n): Yes
For Release Nums: 7.0.5

Changing a Time Aggregation Series Slot's display attributes (scaled unit, 
precision and format) from "custom" to "default" was correctly causing the 
erasure of a Unit Scheme "exception" for the slot, but was not causing the 
generation of the "SLOT_USRUNITS_CHANGED" callback.  The Open Slot Dialog 
responds to that callback by updating the display table's column header 
(where the scaled unit is shown).

With a change in method SlotTimeAggConfigDlg::unitsDefaultRadio_toggled 
(bool), that callback is now correctly being generated.