import wx

app = wx.App()
win = wx.Frame(
  None,
  title="simple editor",
  size=(410, 335))

bkg = wx.Panel(win)


def openFile(evt):
  dlg = wx.FileDialog(
    win,
    "Open",
    "",
    "",
    "All files (*.*)|*.*",
    wx.FD_OPEN | wx.FD_FILE_MUST_EXIST)
  filepath = ''
  if dlg.ShowModal() == wx.ID_OK:
    filepath = dlg.GetPath()
  else:
    return
  filename.SetValue(filepath)
  fopen = open(filepath)
  fcontent = fopen.read()
  contents.SetValue(fcontent)
  fopen.close()


def saveFile(evt):
  fcontent = contents.GetValue()
  fopen = open(filename.GetValue(), 'w')
  fopen.write(fcontent)
  fopen.close()

openBtn = wx.Button(bkg, label='open')
openBtn.Bind(wx.EVT_BUTTON, openFile)

saveBtn = wx.Button(bkg, label='save')
saveBtn.Bind(wx.EVT_BUTTON, saveFile)

filename = wx.TextCtrl(bkg, style=wx.TE_READONLY)
contents = wx.TextCtrl(bkg, style=wx.TE_MULTILINE)

hbox = wx.BoxSizer()
hbox.Add(openBtn, proportion=0, flag=wx.LEFT | wx.ALL, border=5)
hbox.Add(filename, proportion=1, flag=wx.EXPAND | wx.TOP | wx.BOTTOM, border=5)
hbox.Add(saveBtn, proportion=0, flag=wx.LEFT | wx.ALL, border=5)

bbox = wx.BoxSizer(wx.VERTICAL)
bbox.Add(hbox, proportion=0, flag=wx.EXPAND | wx.ALL)
bbox.Add(
  contents,
  proportion=1,
  flag=wx.EXPAND | wx.LEFT | wx.BOTTOM | wx.RIGHT,
  border=5)

bkg.SetSizer(bbox)
win.Show()
app.MainLoop()