Crash when opening "subcontainer"

[pacemdei]

FreeCAD crashes immediately, when using one of the Material buttons that start a dialog using subcontainer.
(Import MaterialX file, GPUOpen Material Library, AmbientCG Material Library)
The external client, however starts and is functional.

The corresponding error message in the log file is

Err: /Users/USER/Library/Application Support/FreeCAD/Mod/Render/./Render/subcontainer.py:221: RuntimeWarning: libshiboken: Overflow: Value 5032641280 exceeds limits of type  [signed] "i" (4bytes).
  self.winid_available.emit(argument)
Err: Err: OverflowErrorErr: Err:

This happened on MacOS 15.4 (24E248).

[sax1johno]

Confirmed that this is also happening on Mac OSX 15.6.1 (getting the same error):

OS: macOS 15.6.1
Architecture: arm64
Version: 1.0.2.39319 (Git) Conda
Build type: Release
Branch: (HEAD detached at 1.0.2)
Hash: 256fc7eff3379911ab5daf88e10182c509aa8052
Python 3.11.13, Qt 5.15.15, Coin 4.0.3, Vtk 9.3.0, OCC 7.8.1
Locale: C/Default (C)
Stylesheet/Theme/QtStyle: FreeCAD Dark.qss/FreeCAD Dark/Fusion
Installed mods: 
  * woodworking 1.1.0.dev.1.1.1.2025.10.20
  * Assembly4.backup1761237977.254292 (Disabled)
  * A2plus 0.4.68
  * fasteners 0.5.43
  * LCInterlocking
  * Assembly4
  * Render

Process:               freecad [21341]
Path:                  /Applications/FreeCAD.app/Contents/Resources/bin/freecad
Identifier:            freecad
Version:               ???
Code Type:             ARM-64 (Native)
Parent Process:        launchd [1]
User ID:               501

Date/Time:             2025-10-23 11:19:12.0387 -0700
OS Version:            macOS 15.6.1 (24G90)
Report Version:        12
Anonymous UUID:        809138CE-D844-EE88-0EDD-DAE77E6DF302

Sleep/Wake UUID:       E540FEEC-B66B-4AD7-AC16-D88EFBD6F27E

Time Awake Since Boot: 740000 seconds
Time Since Wake:       1017 seconds

System Integrity Protection: enabled

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000045fc75c0
Exception Codes:       0x0000000000000001, 0x0000000045fc75c0

Termination Reason:    Namespace SIGNAL, Code 11 Segmentation fault: 11
Terminating Process:   exc handler [21341]

[sax1johno]

Update: It looks like winId() and fromWinId() are not fully implemented in Qt 5 for non-Qt child processes in Cocoa.