import Tkinter as TK

class Row(TK.Frame):
    handle = (lambda x,y: True)

    def setup(self, labels):
       for x in labels:
            b = TK.Button(text=x, command=(lambda: self.handle(x)))
            b.pack({'side':'left', 'expand':'yes'})
            self.buttons.append(b)

    def __init__(self, parent,row):
        TK.Frame.__init__(self, parent)
        self.buttons = []
        self.setup(row)


class KeyPad(TK.Frame):
    def __init__(self, parent):
        TK.Frame.__init__(self,parent)
        self.rows = []
        self.setup()

    def addRow(self, row):
        x = Row(self,row)
        self.rows.append(x)
        x.pack({'side':'top','expand':1})

    def setup(self):
        pass

x = TK.Tk()
TK.Wm.title(x,'Test')
kp = KeyPad(x)
kp.addrow('abc')
kp.addrow('def')
kp.mainloop()