appEntry.py

from tkinter import Entry, CENTER, SOLID, END


class AppEntry(Entry):
    def __init__(self, container, number, _column, _row):
        Entry.__init__(self, container)
        self.number = number

        settings = {'relief':               SOLID,
                    'bg':                   '#424242', 
                    'fg':                   'white',
                    'width':                3,
                    'font':                 ('Verdana', 24), 
                    'highlightthickness':   0.1, 
                    'highlightbackground':  'black', 
                    'justify':              CENTER}

        geometry = {'column':   _column,
                    'row':      _row,
                    'ipadx':    1,
                    'ipady':    3}
        
        self.insert(0, self.number)
        self.configure(**settings)
        self.grid(**geometry)

    def mouse_in_entry(self, mouse):
        self.delete(0, END)

    def mouse_out_entry(self, mouse):
        if self.get():
            mouse.widget.__dict__['number'] = self.get()
        else:
            self.insert(0, mouse.widget.__dict__['number'])

    def __dir__(self):
        return AppEntry.__dict__