[Tkinter] Extrakt a Variable from a closed tkinter window

[woooee]

If you want to access a variable after the tkinter window closes, then you have to make it an instance object. Snipped version of your code

        def change_dropdown(*args):
           self.remaining_variable=self.tkvar.get()
           print(self.tkvar.get() )
            
        # link function to change dropdown
        self.tkvar.trace('w', change_dropdown)
 
 
master = tkinter.Tk()
master.title("Sheetauswahl") 
app = App(master)
master.mainloop()
 
## app=instance,  App=class
## app remains until you destroy it or close the program
print(app.remaining_variable)
sheet = app.remaining_variable
df = pd.read_excel(Filename, sheet_name=sheet)