[Tkinter] can i had a cefpython3 to a labelframe

[deanhystad]

This code really belongs in class MainFrame.__init__

    left = tk.LabelFrame(app, text="", padx=5, pady=5, highlightbackground="black",
                         highlightthickness=2)
    left.grid(row=0, column=0, rowspan=99, sticky='ne', pady=2)
 
    home_browser = tk.LabelFrame(app, text="", padx=5, pady=5, highlightbackground="black",
                                 highlightthickness=2)
    home_browser.grid(row=0, column=1, rowspan=99, sticky='ne', pady=2)
 
    right = tk.LabelFrame(app, text="", padx=5, pady=5, highlightbackground="black",
                                 highlightthickness=2)
    right.grid(row=0, column=2, rowspan=99, sticky='ne', pady=2)

left is placed in the same grid cell as navigation_bar

    left.grid(row=0, column=0, rowspan=99, sticky='ne', pady=2)
       self.navigation_bar.grid(row=0, column=0,
                                 sticky=(tk.N + tk.S + tk.E + tk.W))

I don't know, but think this may be your main problem because it removes the Navigation bar, and thus the browser, from the MainFrame. As mentioned in the comments in get_window_handle, the MAC version is kind of brittle and it is easy to make it crash.

# There is still one issue with this solution. Sometimes there is more than one window, for example when application
# didn't close cleanly last time Python displays an NSAlert window asking whether to Reopen that window. In such
# case app will crash and you will see in console:
# > Fatal Python error: PyEval_RestoreThread: NULL tstate1

That is the error message you are getting when your program crashes.

Why are you setting rowspan=99? Is that a sloppy way to say "I am the only thing in this column?" Sloppy meaning imprecise, not bad. Maybe bad.