Selection bounding box and anchor visualization not correct for Positioner

If items are placed in a layout/positioner and anchored the bound rectangle and anchor indicators are not always correct.

How to reproduce:

(1) Create 5 items (e. g. radio buttons)
(2) Select all 5 items and use the context menu to layout them in a column.
(3) Anchor the column to the right and left
(4) Reset the anchor margins in the property editor
(5) See screenshot. The column should expand to the width of the parent.