code: def focusin(self, event):
          
          self.old_value = self.get()
          bc = self.style.lookup("TEntry", "bordercolor", ("focus",))
          dc = self.style.lookup("TEntry", "darkcolor", ("focus",))
          lc = self.style.lookup("TEntry", "lightcolor", ("focus",))
          self.style.configure("%s.spinbox.TFrame" % self.frame, bordercolor=bc,
                               darkcolor=dc, lightcolor=lc)
docs: Change style on focus in events.