The `Part::Spline` object is the parent of the parametric
Surface Workbench objects.
For example, the `Part::Spline` object is created by the
`Surface_CurveOnMesh` tool, which in reality just calls
the `MeshPart_CurveOnMesh` tool.
See bug description:
https://bitbucket.org/Coin3D/coin/pull-requests/119/fix-sochildlist-auditing/diff
Because of path based rendering (SoFCPathAnnotation) in mouse over
highlight, this bug causes crash more frequently here comparing to
upstream.
All C++ calling of SoGroup::removeAllChildren() is replaced by
Gui::coinRemoveAllChildren(), and python code is fixed by monkey
patching SoGroup.removeAllChildren() in FreeCADGuiInit.py.