Bug 5999 (part 1) Followup: Obj Viewer Obj Tabs: Persist Tree Open State on Attributes Tab
Bug Number: 5999 (part 1) followup
Release notes (y/n): Maybe (in 7.2.1) 
For Release Nums: 7.3 and 7.2.1

One part of the Gnats 5999 fix to the Object Viewer had been "stability" for 
the treeview item Open/Closed states for the Slots, Methods and Account 
Methods subtabs when switching between Object tabs. That fix overlooked the 
fact that AggObj Elements can ALSO have distinct Object Attributes, so the 
"Attributes" tabs can also have a multiple-level treeview in which the 
Open/Closed states needs to persist when switching between Object tabs.

This commit adds treeview item Open/Closed stability fix to the "Attributes" 
subtab (relevant for only Aggregate Objects).

See this new data structure in Q3GUI/OpenObjectDlg.cpp:

  QMap<SimObj*, OpenObjectDlg::StringSet>
    OpenObjectDlg::_expandedObjAttbsListItemHashSetMap;

---