Hi all,
I think, that there is an additional problem, if you use groups.
The objects in the attached document are named according their z-Index:
OneLine (horizontal)
TwoGroup (having green shapes)
ThreeRectangle (orange)
FourGroup (having orange shapes)
FiveCircle (green)
SixRectangle (green)
SevenLine (Vertical)
EightCircle (orange)
NineRectangleBackground (red)
The rendering order in LibreOffice is from back to top:
NineRectangleBackground (red)
OneLine (horizontal)
FiveCircle (green)
SixRectangle (green)
ThreeRectangle (orange)
EightCircle (orange)
SevenLine (Vertical)