1) changes in class
hra_gui.qt.custom_widgets.modelviews.WidgetsHorizontalHeader:
rebuild mechanism of generating custom header line (used by QTableView)
add 2 signals:
sectionResized(int, int, int)
sectionMoved(int, int, int)
(add signals identifiers in hra_gui.qt.utils.signals package)

and override a method:
def showEvent(self, qShowEvent)

add a private method:
def __show_sections__(self, indexes)
the 'engine method' which set up the geometry of indexed elements of a
header view

the reason fo the above changes is to improve display of header widgets
during scrolling of table contents

2) changes in class 
hra_gui.qt.widgets.table_view_widget.TableViewWidget(QTableView, Common)
concerning scrolling of table view contents :

def setScrollContentsByHandler(self, _handler)
	set up a handler which will be invoked when scrolling happens
	this method is used in WidgetsHorizontalHeader constructor to set up
        functionality which have to be invoked on behalf of
WidgetsHorizontalHeader
	to correctly change horizontal header's contents

def scrollContentsBy(self, dx, dy)
	overriding a method invoked when scrolling happens;
	if scroll contents handler is specified it is invoked