Tkinter GUIs always have a root window, whether you get
it by default or create it explicitly by calling the
Tk object constructor. This main root window
is the one that opens when your program runs, and it is where you
generally pack your most important widgets. In addition, Tkinter
scripts can create any number of independent windows, generated and
popped up on demand, by creating
Toplevel widget objects.
Toplevel object created
produces a new window on the display and automatically adds it to the
program’s GUI event-loop processing stream (you don’t need to call the
mainloop method of new windows to
activate them). Example 9-3
builds a root and two pop-up windows.
Example 9-3. PP3E\Gui\Tour\toplevel0.py
import sys from Tkinter import Toplevel, Button, Label win1 = Toplevel( ) # two independent windows win2 = Toplevel( ) # but part of same process Button(win1, text='Spam', command=sys.exit).pack( ) Button(win2, text='SPAM', command=sys.exit).pack( ) Label(text='Popups').pack() # on default Tk( ) root window win1.mainloop( )
toplevel0 script gets a
root window by default (that’s what the
Label is attached to, since it doesn’t
specify a real parent), but it also creates two standalone
Toplevel windows that appear and function
independently of the root window, as seen in Figure 9-3.
Figure 9-3. Two Toplevel windows and a root window
Toplevel windows ...