What controls automated window resizing in Tkinter?

Question

Tkinter top level windows seem to have two \"modes\": where the size is being determined by the application, and where the user controls the size. Consider this code:

Answer 1

The rule is pretty simple - a toplevel window has a fixed size whenever it has been given a fixed size, otherwise it "shrinks to fit".

There are two ways to give the top level window a fixed size: the user can resize it manually, or your application code can call wm_geometry to give it a size at startup.

To reset the original behavior, give the window a null geometry. For example:

def __init__(self,parent):
    ...
    self.b2 = Button(self, text="Reset", command=self.b2Press)
    self.b2.pack()

def b2Press(self):
    self.winfo_toplevel().wm_geometry("")