code: def fix(self):
          
          a = self.childWindow.winfo_geometry().split('+')[0]
          b = a.split('x')
          w = int(b[0])
          h = int(b[1])
          self.childWindow.geometry('%dx%d' % (w + 1, h + 1))
docs: Fix a problem with Tkinter Buttons in Mojave.
          See https://stackoverflow.com/questions/52529403/button-text-of-tkinter-not-works-in-mojave