I'm on Mac High Sierra (10.13.6), XCode 10.1, macports, Python 3.11.5, yada, yada.
In glumpy/app/init.py line 262,

for window in backend.windows():
## update a bunch of timers code here..

something in the loop changes the backend.windows() dict object size, generates the error:

File "/opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/glumpy/app/init.py", line 317, in run
clock = init(clock=clock, framerate=framerate, backend=backend)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/opt/local/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/glumpy/app/init.py", line 262, in init
for window in backend.windows():
RuntimeError: dictionary changed size during iteration

The fix: change the line to..
for window in list(backend.windows()):