Python - tkinter - opencv -> how to run app and open camera at the same time?

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Ubuntu

Python3.6

Hello guys.I'm using tkinter for first time and I want to know if/how can I run app to do some things while I have my camera enabled.I can do it via terminal ,but how can I do it with tkinter?
For example, I want to click a button (named "Camera") to open my camera and at the same time I want to do other things without waiting (I want multitasking).
In open_camera(...) function below, I don't have while loop.
Also I want to know if mainloop() of tkinter is like while loop??
I don't know this information,so I don't use while loop in open_camera(...).
I hope I'm clear.

What I have tried:

from tkinter import *
import tkinter

from camera_record import * # this is my file to open camera(do not contain while loop)
window = tkinter.Tk()
window.geometry("1300x800")
window.title("Vehicle Control")

def GUI_camera():
    open_camera(True , "")
    
Drive_button = Button(window , text = "Camera" , bg = "aqua" , width = 20 , command = GUI_camera)
Drive_button.place(x = 0 , y = 0)
Drive_button.pack()
window.mainloop()

In a few days I will teach myself tkinter by wathcing tutorials.
These days I have exams :P
Thanks in advance.