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How can I add custom Frame objects to custom ttk Notebook in Tkinter/python3?

I am creating a Tkinter/Python3 application where the main window inherits from Notebook (i need tabs), and each tab should be a custom class inheriting from Frame (I would then dynamically use matplotlib to create custom graphs).
Unfortunately I don't seem to be able to have Notebook accept my custom Frames.
Following very reduced snippet of code:
#!/usr/bin/env python3
from tkinter import *
from tkinter.ttk import Notebook
class MyFrame1(Frame):
def __init__(self, master=None, mytext=""):
super().__init__(master)
self.create_widgets(mytext)
def create_widgets(self, mytext):
self.label = Label(self.master, text=mytext, anchor=W)
# this is not placed relative to the Frame, but to the
# master
# 1. How I get the relative coordinates inside the frame
# to be 10, 10 of the frame area?
self.label.place(x=10, y=10, width=128, height=24)
class MyNotebook(Notebook):
def __init__(self, master=None):
super().__init__(master)
self.create_widgets()
def create_widgets(self):
self.f1 = MyFrame1(self, "abc")
# once the UI is drawn, the label "def" seems to overlay
# "abc" even when "f1" is selected
# 2. Why is self.f2 always shown even when self.f1 is
# selected?
self.f2 = MyFrame1(self, "def")
self.add(self.f1, text="f1")
self.add(self.f2, text="f2")
# Without this command nothing gets drawn
# 3. Why is this? Is this equivalent of 'pack' but for
# pixel driven layout?
self.place(width=640, height=480)
def main():
root = Tk()
root.minsize(640, 480)
root.geometry("640x480")
app = MyNotebook(master=root)
# this works as intended the label is indeed placed
# in the frame at 10, 10
#app = MyFrame1(master=root, mytext="123abc")
app.mainloop()
return None
if __name__ == "__main__":
main()
As per comments I have the following main question: why aren't my custom instances of MyFrame1 properly displayed inside MyNotebook?
Sub questions:
How can I get relative coordinate areas of where the frame is located when place my elements (in this case a Label)?
Why even when self.f1 tab is selected in the UI, I can still see the content of self.f2 tab?
Is self.place required in order to show all sub-elements when not using pack?
If I dynamically create Tkinter elements after the MyNotebook is initialized, will those be bound to respective tabs?
Not sure what I'm doing wrong?
Thanks!

Not sure what I'm doing wrong?
Your create_widgets method needs to add widgets to self, not self.master.
How can I get relative coordinate areas of where the frame is located when place my elements (in this case a Label)?
I don't understand what you mean by this. When you use place, coordinates will be interpreted relative to the frame. However, I strongly advise against using place. Both pack and grid will trigger the frame to resize to fit its children which almost always results in a more responsive UI
Why even when self.f1 tab is selected in the UI, I can still see the content of self.f2 tab?
Because you added internal widgets to self.master instead of self.
Is self.place required in order to show all sub-elements when not using pack?
No. It is required to use a geometry manager but it doesn't have to be place. Usually, place is the least desirable geometry manager to use. pack and grid are almost always better choices except for some very specific situations.
If I dynamically create Tkinter elements after the MyNotebook is initialized, will those be bound to respective tabs?
They will be in whatever tab you put them in.
Finally, I would suggest that you remove self.place in create_widgets. Instead, call pack, place, or grid in the same block of code that creates an instance of that class.
It's a bad practice for a widget to add itself to another widget's layout. The code that creates the widget should be the code that adds the widget to the layout.

Python: why must Tkinter class instantiation use a Frame?

If I want to create a Tkinter GUI simply with statements, I can do this:
from Tkinter import *
root = Tk()
root.title("Test Window")
tkFrame = Frame(root)
tkButton = Button(tkFrame)
[...]
The documentation, however, advises that Tkinter be used with a class definition, subclassing a Frame widget:
class App(Frame):
[...]
I would like to understand why that is so. Why can't we subclass the Frame's container, the window? It appears that is what is done with statements in the first example, so why not in a class definition?
EDIT (following Bryan Oakley's answer):
I would like to instantiate at the highest level of Tkinter, which I assume to be Tk() (though I have come across references stating Frame is the top level, but never mind). Indeed, the following will create a window:
from Tkinter import *
class Application(Tk):
pass
app = Application()
app.mainloop()
...but as soon as I try to add widgets I either get errors or two windows, with the widgets in a new window, depending on how I structure the code. Here's a basic example that will produce a second window with the button:
from Tkinter import *
class Application(Tk):
tkBtn = Button()
tkBtn.pack()
app = Application()
app.mainloop()
Anything more, using self, __init__, etc., produces errors. Could someone point me to working code that instantiates Tkinter at the highest level? Just like all the Frame subclasses I'm seeing, but at the highest level?

There is nothing that says a tkinter class must inherit from a frame. You can inherit from any of the tkinter widgets, or any other classs. If you have found documentation that states otherwise, that documentation is wrong. Using Frame is a logical choice since it is designed to be a container of other widgets, but it is not the only choice.
Personally I inherit from a frame because I find it convenient. Some of my GUIs need the ability to open more than one identical window. By having my main code in a Frame I am able to create multiple windows simply by creating multiple instances of the frame, and packing them in Toplevel widgets.
When you inherit from Tk, you can only have a single instance. In the real world that's usually enough, and there's absolutely nothing wrong with doing it that way. Since I personally write a fair number of tkinter programs, having them all start out exactly the same is convenient for me.
Another good choice is a Canvas since you can easily add a background image, which is not something you can do with a Frame.
Bottom line: you are absolutely not required to inherit from Frame. Inherit from whatever you want.
(the following was written in response to an edit of the original question)
In reference to this code:
from Tkinter import *
class Application(Tk):
tkBtn = Button()
tkBtn.pack()
app = Application()
app.mainloop()
The reason you see two windows is that you're not creating the class properly. You need to call the __init__ method of the superclass before creating widgets, because that's what actually creates the root window. Because you don't, you end up with two windows. You get one that is created implicitly when you add a button to a not-yet-constructed root window, and you get another when your subclass finishes initializing.
The solution is to not take shortcuts, and instead initialize the class properly:
from Tkinter import *
class Application(Tk):
def __init__(self):
Tk.__init__(self)
tkBtn = Button()
tkBtn.pack()
app = Application()
app.mainloop()
Note that this isn't a tkinter-specific problem. When subclassing, unless you have explicit reasons to do otherwise, you always should call the __init__ method of the superclass.
You asked for working examples, here are a couple:
https://stackoverflow.com/a/22424245/7432
https://stackoverflow.com/a/11405393/7432
You might also want to read the responses in the question Inheriting from Frame or not in a Tkinter application

How to get the name of a widget Python Tkinter

I am working on a program where I create some widgets in a for loop. So I need to get the name of them dynamically. I have set up is when the mouse enters the frame. Which holds the two text label widgets. I causes a function to run. And I want to change the background color of a widget with the name of noteName. But I seem to have run into a stopping point and I can no figure it out. I have searched online but could not find much. SO does anyone here know how to get the name of a widget?
Code:
def get_children_hover(event):
for widgets in event.widget.winfo_children():
#This is here where I can not seem to figure out how to get the widgets name.
Can someone push me into the right direction.

winfo_children() is the right thing to use but you are using it wrong. It is a method for parent widgets. (i.e. root, frame, canvas etc..)
Also:
If the order doesn’t matter, you can get the same information from the
children widget attribute (it’s a dictionary mapping Tk widget names
to widget instances, so widget.children.values() gives you a list of
instances).
simple example:
import tkinter as tk
def foo():
print ("Frame:", frm.winfo_children())
print ("Root:", root.winfo_children())
print ("children_values:", root.children.values())
root = tk.Tk()
frm = tk.Frame(root)
tk.Label(root,text="foo").pack()
btn = tk.Button(frm,text="FOOO",command=foo)
frm.pack()
btn.pack()
root.mainloop()
about your code:
def get_children_hover(event):
for widgets in root.winfo_children(): #assuming your Tk() instance named root

Change label text from variable

I am trying to write a program that has twenty five buttons, when one is pressed, it will read from a text file, store it in a variable, then make the text of the label at the bottom of the page change to the text of the text file. Here is my code so far:
from Tkinter import*
box1 = 'C:/Users/Geekman2/Documents/Tests/box1.txt'
var = StringVar()
var.set("man")
def openfile(filename):
filetxt = (open(filename,"r").read())
#filetxt.set(iletxt)
print filetxt
return filetxt
def Box1():
openfile(box1)
openfile(box1)
donut = Tk()
donut.geometry('450x450')
cupcake = Button(donut,text = "Box #1", command= Box1 )
cupcake.pack()
Whatsin = Label(donut,textvariable = var)
Whatsin.pack(side =BOTTOM)
donut.mainloop()
These two lines are giving me trouble, whenever I uncomment them and try to run the program I get the error "AttributeError: 'NoneType' object has no attribute 'tk'"
var = Stringvar()
var.set("man")
Can anyone tell me what might be the cause of this? I know what the error means, but as far as I can tell it doesn't apply in this situation

You need to instantiate an instance of Tk before you can use StringVar. Move donut = Tk() before your lines and it should work.

StringVar (as well as other Tkinter variable) are wrappers around Tcl variable1.
Your error come from creating a StringVar before the Tcl interpreter is initialized.
Thus you might call Tk()(which perform such initialisation) before creating your variables.
If you look at StringVar constructor signature: __init__(self, master=None, value=None, name=None) you see that as other Tkinter objects, the constructor accepts a master as first argument. This master is essentially needed to access the Tcl interpreter. If not provided, there is a fallback to a global Tkinter.Tk instance _default_root, which is None in your case. Asking the Tcl interpreter (field named tk) on it raise the AttributeError.
Note that for widgets, not providing master lead to the creation of a default one, but not on variables.
1 the whole Tkinter toolkit is a wrapper around a Tcl toolkit called Tk. Tcl variables allow to be traced, ie bind callback on variable change. Tk heavily use this mechanism and thus, Tkinter has to provide access to Tcl variables.

tk destroy() and grid_forget() don't always work

i'm hoping anyone can help me out here. i'm having an issue with a tkinter gui i built. the issue only happens in windows. My GUI creates a results frame with some labels in it, when it's time to calculate something else, the user clicks on the "newPort" button and that button is supposed to remove the results frame and set to False some instance attributes internal to the calculation. The issue i'm having, which is apparent only in windows is that sometimes the results frame, and its descendant labels don't disappear every time. Sometimes they do, sometimes they don't. The instance variable is correctly set to False but the widgets are still visible on the main GUI. The GUI also contains a couple checkboxes and radiobuttons but they don't impact the creation of the results frame nor its expected destruction. I have not been able to pin point a pattern of actions the user takes before clicking on the newPort button which causes the frame and labels to not get destroyed. This happens when i freeze my app with py2exe, as well as running the app from the python interpreter within the eclipse IDE. I have not tried running the app from the python interpreter directly (i.e. without the IDE) and this problem does not happen on my Mac when i run the app using the eclipse python interpreter. Thanks very much all! My code looks like this:
import Tkinter as TK
class widget(object):
def __init__(self,parent=None):
self.parent = TK.Frame(parent)
self.parent.grid()
self.frame = TK.Frame(self.parent)
self.frame.grid()
newLedger = TK.Button(self.parent,command=self.newPort).grid()
self.calcButton = TK.Button(self.frame,command=self.showResults)
self.calcButton.grid()
self.calcVariable = True
def newPort(self):
self.calcVariable = False
try:
self.second.grid_forget()
self.first.grid_forget()
self.resultsFrame.grid_forget()
self.second.destroy()
self.first.destroy()
self.resultsFrame.destroy()
except:
raise
self.frame.update_idletasks()
def showResults(self):
self.resultsFrame = TK.Frame(self.frame)
self.resultsFrame.grid()
self.first = TK.Label(self.resultsFrame,text='first')
self.first.grid()
self.second = TK.Label(self.resultsFrame,text='second')
self.second.grid()
if __name__ == '__main__':
root = TK.Tk()
obj = widget(root)
root.mainloop()

You don't need to destroy or call grid_forget on the labels, and you don't need to call grid_forget on the resultsFrame; when you destroy the resultsFrame it will cause all off its children to be destroyed, and when these widgets are destroyed they will no longer be managed by grid.
The only way I can get widgets to not be destroyed is if I click on the "calc" button twice in a row without clicking on the "new" button in-between. I'm doing this by running your program from the command line.