Print Message in Text Widget that is part of a class - python-2.7

Question

I am fairly new to object-oriented programming. I have a class called MessageWindow which generates a Tkinter text widget inside of a Frame. In my main function I want to write a message into the text widget but when I run the program I get: Class MessageWindow has no attribute text1
I've tried following other responses here on Stack overflow, and another tutorial on the web and I always end up back at the same error
from Tkinter import *
class MessageWindow(Frame):
def __init__(self, master):
Frame.__init__(self, master)
self.pack(fill='both', expand='yes')
self.text1 =Text(self,height=9, width=13)
self.text1.pack()
def main():
root=Tk()
root.title("MessageWindow")
app = MessageWindow(root)
root.mainloop()
MessageWindow.text1.insert(END,"This is a test Message")
MessageWindow.text1.pack()
if __name__=='__main__':
main()
Any help would be appreciated. I need to understand this for a larger GUI project that I am working on.

Answer 1

Ok so
1. You are referring to MessageWindow as your class object when you should be referring to app, as you have instantiated the class as 'app' in your main definition.
2. Your root.mainloop() should be after all your GUI code as it will not take affect if it is after/outisde the mainloop.
So this is the How the code is supposed to be:
from Tkinter import *
class MessageWindow(Frame):
def __init__(self, master):
Frame.__init__(self, master)
self.pack(fill='both', expand='yes')
self.text1 = Text(self,height=9, width=13)
self.text1.pack()
def main():
root=Tk()
root.title("MessageWindow")
app = MessageWindow(root)
# Fix one
app.text1.insert(END,"This is a test Message")
app.text1.pack()
# Fix two
root.mainloop()
if __name__=='__main__':
main()