SCT / Qt5 Fixes: Column hiding, widths and reside mode problems [5877]
Bug Number: 5877
Release notes (y/n): Yes
For Release Nums: 7.1 and, after testing, 7.0.2

Gnats 5877: SCT display issues when cutting (removing) a slot.

In certain transitions, the SCT data column header widths (horizontal 
QHeaderView on the data table) were not being assigned the proper 
attributes.  This _seems_ to be some buggy behavior in Qt 5.5.1's 
QHeaderView class -- see this unanswered question on the Qt Forum, 
and our related bug: 5856.

   Can't hide QTableView column after 'resetting' the QAbstractTableModel
   https://forum.qt.io/topic/74052

We were unable to fix this without deleting and recreating the data 
table's horizontal QHeaderView.  In doing so, more re-initializations 
were required.  

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