This is related to the issue https://github.com/nltk/nltk/issues/2429 .
I will repeat the details of the issue here to get quicker replies from the community.
I looked at the code of a drawing demo:
nltk/nltk/draw/util.py
Lines 2534 to 2538 in 33ac28c
cf = CanvasFrame(closeenough=10, width=300, height=300)
c = cf.canvas()
ct3 = TextWidget(c, "hiya there", draggable=1)
ct2 = TextWidget(c, "o o\n||\n___\n U", draggable=1, justify="center")
co = OvalWidget(c, ct2, outline="red")
And trying to insert some Chinese characters in line 2537, I get the following picture:
On the left hand side is rendered by the demo, the right hand side is using the button Print to Postscript.
We can see that actually the rendering is successful as the bold song ti text 可以的 is shown. However, the exporting to ps failed. Not only the Characters but also some math symbols are not exported.
But I am not good at tkinter, so my trial to fix this failed.
I hope someone else can help to fix this.