QTreeView draws the different sub-rects of an item's background over
multiple calls to drawPrimitive(PE_PanelItemViewRow). The item row is
not separately stylable, but the item might have a styled background
property. To get a consistent background, we must use the item's
background rule when filling the item's row background.
To fix that, delegate the filling of the branch background to
drawPrimitive(PE_PanelItemViewRow), and implement PE_PanelItemViewRow
handling to render the rule for the ViewItem pseudo element if there is
a background rule defined for it.
Add a baseline test stylesheet for this scenario. Note that the selection
in an item view is better styled via the selection-background-color
qss property.
Task-number: QTBUG-73251
Task-number: QTBUG-106227
Pick-to: 6.4 6.2
Change-Id: I5d0c170f78009fe5015dd749975e6df27485b3b8
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
483ae6c448