Issue with tkinter Root Window and Radio Button GUI Generation - python-3.x

Question

As someone new to tkinter for Python 3, I am having a couple of little issues navigating how to generate a GUI (in context of a Python script) despite reading the documentation and Stack Overflow answers. My objective is to create a frame with 7 radio button choices each corresponding to a screen resolution size which when selected and the submit button is pressed, the selected radio button will pass its value to a variable. However when I implement my GUI, I get two issues.
The first is that my frame opens correctly with the radio buttons, but another frame, which is blank and is titled "tk" appears. Regardless of what I do (i.e. use root.withdraw() etc. as others have mentioned), this blank window still appears.
The second and more baffling issue I am having is that when generated, all but the first radio button is selected, not normally with a dot in the center, but with a hyphen. Now the user can press on the option he/she wants and it will all unselect except for the choice, but it doesn't look normal and would probably confuse the user. I read about setting tristatevariable to none yet that didn't work (or at least in my trial). I also tried to force a deselect() function on all of the radio buttons before they generate and that didn't work either. Also, keep in mind that the radio buttons' variable must handle a string and not an int. What is happening here and how can I fix it?
The code snippet that pertains to both of these seemingly related issues is as follows:
if urldata == None:
class ResolutionInputGUI:
def __init__(self, master):
self.master = master
master.title("My GUI")
self.label = tk.Label(master, text="Your Screen Resolution Is: " + screenres + "\n")
self.label.pack()
MODES = [
("500×500", "500×500"),
("1280×800", "1280×800"),
("1280×1024", "1280×1024"),
("1440×900", "1440×900"),
("1680×1050", "1680×1050"),
("1920×1080", "1920×1080"),
("1920×1200", "1920×1200")
]
resolution = tk.StringVar()
resolution.set("500×500")
for text, mode in MODES:
self.radiobutton = tk.Radiobutton(master, text=text, variable=resolution, value=mode)
self.radiobutton.pack(anchor=tk.W)
self.submit_button = tk.Button(master, text="Submit", command=self.submit)
self.submit_button.pack()
self.cancel_button = tk.Button(master, text="Cancel", command=self.cancelbutton)
self.cancel_button.pack()
def submit(self):
global screenres
screenres = self.radiobutton.get()
root.quit()
self.master.destroy()
print(screenres)
def cancelbutton(self):
raise SystemExit
root = tk.Tk()
my_gui = ResolutionInputGUI(root)
root.mainloop()
Any help would be greatly appreciated as I cant seem to solve this issue and tkinter seems to be much more complicated than originally thought. Also, is there anything else that I am doing inefficiently here or to make the end user experience more "friendly?" Thank you so much!

Answer 1

The first is that my frame opens correctly with the radio buttons, but another frame, which is blank and is titled "tk" appears
This is because you are calling Tk() twice. I see one of them near the end, and you must have another elsewhere in your code.
all but the first radio button is selected, not normally with a dot in the center, but with a hyphen.
This is because you are using a local variable. Change "resolution" to "self.resolution".
when selected and the submit button is pressed, the selected radio button will pass its value to a variable
To do this you need to return the value from the variable, not from the button.
Also, you should put the class definition at the global level.
import tkinter as tk
class ResolutionInputGUI:
def __init__(self, master):
self.master = master
master.title("My GUI")
self.label = tk.Label(master, text="Your Screen Resolution Is: " + screenres + "\n")
self.label.pack()
MODES = [
("500×500", "500×500"),
("1280×800", "1280×800"),
("1280×1024", "1280×1024"),
("1440×900", "1440×900"),
("1680×1050", "1680×1050"),
("1920×1080", "1920×1080"),
("1920×1200", "1920×1200")
]
self.resolution = tk.StringVar(master, value="500×500")
for text, mode in MODES:
self.radiobutton = tk.Radiobutton(master, text=text, variable=self.resolution, value=mode)
self.radiobutton.pack(anchor=tk.W)
self.submit_button = tk.Button(master, text="Submit", command=self.submit)
self.submit_button.pack()
self.cancel_button = tk.Button(master, text="Cancel", command=self.cancelbutton)
self.cancel_button.pack()
def submit(self):
global screenres
screenres = self.resolution.get()
root.quit()
self.master.destroy()
print(screenres)
def cancelbutton(self):
raise SystemExit
if urldata == None:
root = tk.Tk()
my_gui = ResolutionInputGUI(root)
root.mainloop()