Calling a Ptoaster function within a Tkinter GUI class

Question

The Problem

I'm working on a Python GUI , using Tkinter . I'm also trying to add "toaster" messages, using Ptoaster . Here's an example of what I'm trying to achieve:

from tkinter import *
import ptoaster

PADDING = 20

class MyInterface:
    def __init__(self):
        self.root = Tk()
        self.label = self.make_label()
        print_welcome()

    def make_label(self):
        result = Label(self.root, text="Hello, world!")
        result.pack(padx=PADDING, pady=PADDING)
        return result

    def run_me(self):
        self.root.mainloop()

def print_welcome():
    message = "Hello again!"
    ptoaster.notify("Hello!", message)

interface = MyInterface()
interface.run_me()

If I try to run the above code, one of two things will happen:

1. The command line will spit out the following error:

[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
python3: ../../src/xcb_io.c:260: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
XIO:  fatal IO error 25 (Inappropriate ioctl for device) on X server ":0"
      after 207 requests (207 known processed) with 2 events remaining.
Aborted (core dumped)

2. My whole laptop will freeze , necessitating a hard reset.

However, if I move the call print_welcome() from outside of MyInterface, so that it's called before this class is initialised, then none of the above errors crop up.

What I'd Like to Know

1. How to call a function, from within a Tkinter GUI class, which causes a "toaster" message to be displayed, without causing the whole platform to crash.
2. Why the above errors are cropping up.

Answer 1

Documentation states it needs to be verified that the ptoaster.notify is called from the main program.

IMPORTANT - you need to make sure you call notify from the main program

Working code for me:

from tkinter import *
import ptoaster

PADDING = 20

class MyInterface:
    def __init__(self):
        self.root = Tk()
        self.label = self.make_label()
        print_welcome()

    def make_label(self):
        result = Label(self.root, text="Hello, world!")
        result.pack(padx=PADDING, pady=PADDING)
        return result

    def run_me(self):
        self.root.mainloop()

def print_welcome():
    message = "Hello again!"
    ptoaster.notify("Hello!", message)

if __name__ == '__main__':
    interface = MyInterface()
    interface.run_me()

Documentation (See: Sample Program)