BT: Fixed treeview painting regression on Vista
BT: Fixed treeview painting regression on Vista

The old code did not split up the frame from the central
parts of the itemview selection box correctly. We now
draw the edges as border images instead. Previously this
would lead to somewhat ugly scaling artifacts for small
header sections.

Task: 248839
Reviewed-by: ogoffart
(cherry picked from commit 041a8ecdb5f11dfc499f8f8f77d85cb63508c093)

RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,radekp/qt,KDE/qt,KDE/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,KDE/qt,igor-sfdc/qt-wk,RLovelett/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,radekp/qt,RLovelett/qt,radekp/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,radekp/qt,KDE/qt,igor-sfdc/qt-wk,KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,KDE/qt,radekp/qt,radekp/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,KDE/qt,radekp/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,radekp/qt,KDE/qt,radekp/qt,pruiz/wkhtmltopdf-qt