How many threads are there in a simple GUI app?

Question

I noticed that some Exceptions are caught normally by the main thread except: at the end of this code, and some other aren't (1/0 in OnButton). Why ?

Does this mean that OnButton(self, evt) is launched in another thread ?

How many threads are involved in a simple GUI app with wxPython ?

import wx

class MyFrame(wx.Frame):
    def __init__(self, parent):
        wx.Frame.__init__(self, parent, title="Test", size=(300, 300))
        MyPanel(self)

class MyPanel(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent)
        button = wx.Button(self, wx.ID_ANY, "Test")
        self.Bind(wx.EVT_BUTTON, self.OnButton)
        #1/0       here this line would be handled by the try/except below

    def OnButton(self, evt):
        1/0       # when you click on button, why isn't this handled by the exception hanlder?      

try:
    app = wx.App(False)
    MyFrame(None).Show()
    app.MainLoop()
except Exception, e: 
    print 'Hello' + type(e).__name__    

Answer 1

There is only one thread involved in a simple GUI app with wxPython Take a look at the following link.

why you can't use a global exception handler wrapped around the call to the app object's MainLoop method