tkinter application to run processes without getting blocked or hung

Application.py

'''
The aim of this Gist is to give you a base application where you just need to add your own elements/processes and make it work.
'''

import tkinter as tk
from tkinter import ttk,messagebox
import threading
import time

#base GUI Class
class GUI:
    def __init__(self, root, runCommand):
        mf = ttk.Frame(root, padding="5 5 5 5")
        mf.grid(column=0, row=0)
        mf.columnconfigure(0, weight=1)
        mf.rowconfigure(0, weight=1)

        # Global Values
        self.Fnm = tk.StringVar(root, "SearchFile.xlsx")
        self.Ncol = tk.StringVar(root, "D")
        self.Vcol = tk.StringVar(root, "C")
        # Label
        tk.Label(mf, text="File Name").grid(column=1, row=1, pady=6)
        tk.Label(mf, text="Name Col").grid(column=1, row=3, pady=6)
        tk.Label(mf, text="Value Col").grid(column=3, row=3, pady=6)

        # components
        self.fname = ttk.Entry(mf, width=18, textvariable=self.Fnm)
        self.nmCol = ttk.Entry(mf, width=6, textvariable=self.Ncol)
        self.valCol = ttk.Entry(mf, width=6, textvariable=self.Vcol)
        self.but = ttk.Button(mf, text="Refresh", command=runCommand)
        self.pgbar = ttk.Progressbar(mf, orient="horizontal", mode="determinate")

        # Design
        self.fname.grid(column=2, row=1, pady=3, columnspan=3)
        self.nmCol.grid(column=2, row=3, pady=3)
        self.valCol.grid(column=4, row=3, pady=3)
        self.but.grid(column=2, row=2, columnspan=2)
        self.pgbar.grid(column=1,row=4,columnspan=4)

    def refresh(self):
        pass

    def get(self):
        return [self.Fnm.get(), self.Ncol.get(), self.Vcol.get()]

#Base process Class
class Proc:
    def __init__(self, dets,pgbar,but):
        self.Fnm = dets[0]
        self.Ncol = dets[1]
        self.Vcol = dets[2]
        self.pg=pgbar
        self.butt=but

    def refresh(self):
        self.butt['state'] = 'disabled'
        self.pg.start()
        #ATTENTION:Enter Your process Code HERE
        for _ in range(5):
            time.sleep(2)
        self.pg.stop()
        #Any search/sort algorithm to be used
        #You can use self.pg.step() to be more specific for how the progress bar proceeds
        messagebox.showinfo("Process Done","Success")
        self.butt['state'] = 'enabled'

#Base Application Class
class App:
    def __init__(self, master):
        self.master = master
        self.gui = GUI(self.master, self.runit)

    def runit(self):
        self.search = Proc(self.gui.get(),self.gui.pgbar,self.gui.but)
        self.thread1 = threading.Thread(target=self.search.refresh)
        self.thread1.start()

def main():
    app = tk.Tk()
    gui = App(app)
    app.title("Refresh Search File")
    app.mainloop()

if __name__ == '__main__':
    main()