Using Tkinter widgets on child window

[chewy1418]

I tried using the .pack() method, but I still can't get the .insert() to work (Usually the methods associated with the Listbox comes up after I type variableName.). I can, however, do this in my main.py file without any issue. I am guessing this is because I define root = Tk() and then pass that to my Application class.

Is my other class not inheriting the Tk()?