Tkinter grid layout

[William Gill]

Excuse me for intruding, but I followed examples and ended up with a 
similar architecture:

     from Tkinter import *
     class MyMain(Frame):
         def __init__(self, master):
             self.root = master
             self.master=master
     root = Tk()
     app = MyMain(root)
     app.master.title("Object Editor")
     root.mainloop()

Erick, are you saying it should be modified to something like :

     from Tkinter import *
     class MyMain(Tk):
     ...
     ...
     app = MyMain()
     app.title("My App")
     app.mainloop()

Thanks,
Bill

Eric Brunel wrote:
> On Wed, 06 Jul 2005 11:44:55 +0100, Richard Lewis 
> <richardlewis at fastmail.co.uk> wrote:
> 
>> Hi there,
>>
>> I've got a tree control in Tkinter (using the ESRF Tree module) but I
>> can't get it to layout how I want it.
>>
>> I'd like to have it so that it streches north/south (anchored to the top
>> and bottom), is of a fixed width and is anchored to the left hand side.
>> Here's my code (its derived from one of the examples from the ESRF web
>> site):
>>
>> class MainWindow(Frame):
> 
> [snip code]
> 
> First of all, it is not a good idea to make your so-called window 
> inherit from Frame: a Frame is not a window in tk, but a generic 
> container. Creating a Frame without a container window will 
> automatically initialize the tk toolkit, creating a default window which 
> will become the default parent for widgets where you don't specify one. 
> According to the well-known "explicit is better than implicit" 
> principle, if a MainWindow instance are actually the main window for 
> your application, you'd really better inherit from the Tkinter class for 
> the main window, which is Tk. Doing it this way has a lot of advantages 
> over what you do; for example, if you later have to create a menu bar 
> for your application, you will be able to do it in the MainWindow class. 
> If you inherit from Frame, you won't get any access to the actual 
> window, so you won't be able to create a menu in it.
> 
> This may seems to be unrelated to your problem, but it's not: by 
> creating a Frame, you introduce one more unneeded container. So, in some 
> code you don't show here, you have to insert the MainWindow instance 
> into its parent window via a call to its pack or grid method. Since the 
> code you show seems to be correct, I guess the problem is in this call 
> to pack or grid, which probably does not tell the Frame how to behave 
> when its parent window is resized, causing it to get the default 
> behaviour, which is "do nothing at all".
> 
> To be sure this actually is the problem, try to replace the line:
> Frame.__init__(self, master)
> in MainWindow.__init__ by:
> Frame.__init__(self, master, bg='blue', bd=2)
> This way, a blue border will appear around the frame, allowing you to 
> see how it grows.
> Then run your application, and resize the window. You should see that 
> the frame does not grow when the window grows, explaining why your tree 
> deos not grow (in fact, it would grow if its container did; but its 
> container doesn't...)
> 
> So you should either make your MainWindow class inherit from Tk, which 
> eliminates the unneeded container and the problems it may cause, or make 
> sure the pack or grid on your MainWindow instance actually tells the 
> container to grow with its container. With pack, it's quite easy: just 
> do myWindow.pack(fill=BOTH, expand=1). With grid, it's a bit more 
> complicated, since you will have to configure the grid on the container.
> 
> But basically, my advice would be:
> - Never make your windows inherit from Frame; make them inherit from Tk 
> for the main window or from Toplevel for all other ones
> - When you have resize problems, always check the whole widget hierarchy 
> from the actual window down to the widget showing the problem. The cause 
> is very often not on the widget itself, but on one of its containers.
> 
> HTH