[Tkinter] tkinter freezes by clicking button

[Gribouillis]

but even after waiting for several minutes nothing happens.

What happens if you run solvesudo.py alone? After some time it should raise SolutionFound and stop.

Also, based on this answer, you can try to put code in tksudo.py in a if __name__ == '__main__' block, for example

# tksudo.py

if __name__ ==  '__main__':
    from tkinter import Tk, Frame, Entry, Label, Button, IntVar, StringVar, LEFT
    from tkinter import messagebox
    from tkcallasync import tk_call_async, MULTIPROCESSING
    import solvesudo

    def do_solve(sudoku):
        status = solvesudo.wsolve(sudoku)
        return status, sudoku

    disabled = False

    def execute_solver():
        global disabled
        if disabled:
            messagebox.showinfo("warning", "It's still calculating...")
            return

        def callback(result):
            global disabled
            disabled = False
            status, sudoku = result
            solvesudo.printSUDOKU(sudoku)
            result_var.set('Found!' if status else 'Not Found!')

        disabled = True
        tk_call_async(root, do_solve, args=(solvesudo.sudoku,), callback=callback, method=MULTIPROCESSING)

    root = Tk()

    row = Frame(root)
    row.pack()
    Button(row, text="Solve Sudoku", command =execute_solver).pack(side=LEFT)
    Button(row, text="It's responsive", command= lambda: messagebox.showinfo("info", "it's responsive")).pack(side=LEFT)

    result_var = StringVar()
    Label(root, textvariable=result_var).pack()

    root.mainloop()