Import error when called netgen.gui on Big Sur

Hello everybody,

I try to test the i-tutorial of 4.2 Constructive Solid Geometry because I want to start 3D FEM on MacOS 11.6.
But when I import netgen.gui, I face Tcl Error

---

TclError Traceback (most recent call last)
<ipython-input-1-b84eefae61c3> in <module>
----> 1 import netgen.gui
2 from ngsolve import Draw, Redraw # just for visualization

/Applications/Netgen.app/Contents/Resources/lib/python3.9/site-packages/netgen/gui.py in <module>
16 import os
17 if not "NETGEN_DOCUMENTATION_RST_FORMAT" in os.environ:
---> 18 StartGUI()
19
20 def Snapshot(w,h, filename=None):

/Applications/Netgen.app/Contents/Resources/lib/python3.9/site-packages/netgen/gui.py in StartGUI()
9 win.tk.eval('lappend ::auto_path ' + netgen._netgen_bin_dir)
10 # load with absolute path to avoid issues on MacOS
---> 11 win.tk.eval('load "'+netgen._netgen_lib_dir.replace('\\','/')+'/libgui[info sharedlibextension]" gui')
12 win.tk.eval( netgen.libngpy._meshing._ngscript)
13

TclError: dlopen(/Applications/Netgen.app/Contents/MacOS/libgui.dylib, 6): Symbol not found: _OBJC_CLASS_$_NSOpenGLContext
Referenced from: /Applications/Netgen.app/Contents/MacOS/libgui.dylib
Expected in: flat namespace
in /Applications/Netgen.app/Contents/MacOS/libgui.dylib

---

I believe that NSOpenGLContext is deprecated.
Can't I use Netgen for 3D visualization through jupyter notebook or python directly?

I would appreciate it if you give me any comments.

Greetings,
Sat