[Tkinter-discuss] How to launch a dialog when app is started?

[Russell Blau]

I am trying to write a Tkinter application that will automatically display a
particular dialog box on top of the application when it is initialized.
(Like a word processor opening a "File Open" dialog as the first thing that
happens when you enter the application.)  How do I do this?  I have a method
that invokes the dialog box, but I cannot call it until after my app's
mainloop has started; but once the mainloop has started, I can't call it
from the program, either!

I'm sure I'm overlooking something obvious here.

Example (skeleton) code:

from Tkinter import *

class NewPageDialog(tkSimpleDialog.Dialog):
    def body(self, master, title="Select Target"):
        Label(master, text="Target page:").grid(row=0)
        self.targetpage = Entry(master)
        self.targetpage.grid(row=0, column=1)
        return self.targetpage

    def validate(self):
        return True

    def apply(self):
        pass

class GuiApplication(Frame):

    def __init__(self, master):
        Frame.__init__(self, master)

    def newpage(self):
        n = NewPageDialog(self)
        self.targetpage = n.targetpage.get()


if __name__ == "__main__":
    app = GuiApplication(Tk())
    # do something here to cause GuiApplication to invoke newpage() method
when it starts
    app.mainloop()