[Tkinter] Use function from other class (Tkinter)

[zarize]

Thank you very much for your message :)
1)
Yes, it was by a mistake, i fixed it now.

2)My goal is to make an application which has a lot of tabs, and every single tab should have 1 seperate file designed for it(in general 9 tabs). Load_Data is in Application class, because i was thinking that it might be good to stack all functions in main file(Application class).
Purpose of this function is to gather data based on Entries provided by user and display it (later on)

3)
I wanted to treat Rents_tab as other 8 tabs, i would like to store the code down there and access it from the main class - Application