#32488 BIM: Prevent wrapping "Building", and "Level" in objects of other types.

Problem description

In FreeCAD, you can sometimes do completely illogical things. One example is wrapping logical objects in physical ones. For example, you can wrap an entire level or even a building in a window or beam. This becomes even more complicated when the building or level is "active." I completely lose track of what wraps in what and what becomes a child object of what.

This often happens when you accidentally click while a level or building is selected in the tree. But it's very confusing. See the video for a demonstration.

https://github.com/user-attachments/assets/56de4068-03b0-4f4e-a784-ec893aa96e37

There are examples where it's useful to wrap a group of primitives, for example, in a column. This creates a complex column consisting of simple subobjects. But making a window out of a level is very strange.

I understand that these are nothing more than groups. But these entities still have their own properties. And unnecessary nesting is just confusion.

Perhaps we should introduce an artificial limitation that prevents nesting other levels within a level or nesting a building within a window?

Workbench affected?

BIM

Steps to reproduce

Expected behavior

Actual behavior

Development version About Info (in Safe Mode)

OS: Windows 10 build 19045
Architecture: x86_64
Version: 26.3.0dev.20260902 (Git shallow)
Build date: 2026/09/02 02:30:22
Build type: Release
Branch: (HEAD detached at c68c45227)
Hash: c68c452275ec188f35c02f6b30aba880b3783cf1
Python 3.11.14, Qt 6.8.3, Coin 4.0.10 (bundled), Pivy 0.6.11 (bundled), Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, Clipper2 , IfcOpenShell 0.8.2, OCC 7.8.1
Locale: Russian/Russia (ru_RU) [ OS: Russian/Russia (ru_RU) ]
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Light/
QPA/File dialog/Color dialog: windows/via Win32/via Qt
Navigation Style/Orbit Style/Rotation Mode: Revit/Turntable/Drag at cursor
Logical DPI/Physical DPI/Pixel Ratio: 96/92.6073/1
OpenGL version/vendor/renderer: 4.6.0 NVIDIA 581.80/NVIDIA Corporation/NVIDIA GeForce GTX 1060 6GB/PCIe/SSE2
Installed mods:
  * AddFC Workbench 3.7.8
  * Curved Shapes 1.0.15
  * Curves workbench 0.6.81
  * FrameForge 0.2.1
  * Mesh Remodel 1.12.0
  * Parametric Road 1.0.9
  * Reinforcement
  * Road 2026.4.11
  * SheetMetal Workbench 0.8.22
  * Silk workbench 0.4.0
  * SvgWorkbench 1.0.0.dev15
  * Woods 1.1.0

Last known good version (optional)

--