Re-opening second display on OSX

[ghareth]

I have upgraded from pythonocc 0.18.2 running under python 3.6 and qt 5.6 and MacOS Mojave.
I am now running pythonocc 7.4 under python 3.8 and qt 5.9 and MacOS Mojave.

Using pythonocc 0.18.2, it was possible to open a display, use the visualisation and then close the display window. It was then possible to open a second display.

Under pythonocc 7.4, the second qt window opens but displays a dark grey background instead of the visualisation.

For example, the program below does not display the second visualisation.

from OCC.Display.SimpleGui import init_display
from OCC.Core.BRepPrimAPI import BRepPrimAPI_MakeBox

display, start_display, add_menu, add_function_to_menu = init_display()
my_box = BRepPrimAPI_MakeBox(10., 20., 30.).Shape()
display.DisplayShape(my_box, update=True)
start_display()

display, start_display, add_menu, add_function_to_menu = init_display()
my_box = BRepPrimAPI_MakeBox(10., 20., 30.).Shape()
display.DisplayShape(my_box, update=True)
start_display()

[tpaviot]

I cannot reproduce the isse, it works on my Linux laptop, I guess it is osx specific