Tk grid won't resize properly

Question

I'm trying to write a simple ui with Tkinter in python and I cannot get the widgets within a grid to resize. Whenever I resize the main window the entry and button widgets do not adjust at all.

Here is my code:

 class Application(Frame):
     def __init__(self, master=None):
         Frame.__init__(self, master, padding=(3,3,12,12))
         self.grid(sticky=N+W+E+S)
         self.createWidgets()

     def createWidgets(self):
         self.dataFileName = StringVar()
         self.fileEntry = Entry(self, textvariable=self.dataFileName)
         self.fileEntry.grid(row=0, column=0, columnspan=3, sticky=N+S+E+W)
         self.loadFileButton = Button(self, text="Load Data", command=self.loadDataClicked)
         self.loadFileButton.grid(row=0, column=3, sticky=N+S+E+W)

         self.columnconfigure(0, weight=1)
         self.columnconfigure(1, weight=1)
         self.columnconfigure(2, weight=1)

 app = Application()
 app.master.title("Sample Application")
 app.mainloop()

Answer 1

Add a root window and columnconfigure it so that your Frame widget expands too. That's the problem, you've got an implicit root window if you don't specify one and the frame itself is what's not expanding properly.

root = Tk()
root.columnconfigure(0, weight=1)
app = Application(root)