@staticmethod
def get_offset(tk_window):
    """
            Returns an appropriate offset for a given tkinter toplevel,
            such that it always is created center screen on the primary display.
        """
    width_offset = int(tk_window.winfo_screenwidth() / 2 - tk_window.
        winfo_width() / 2)
    height_offset = int(tk_window.winfo_screenheight() / 2 - tk_window.
        winfo_height() / 2)
    return width_offset, height_offset
