Core Python Programming (2nd Edition)

Lines 537
Here we instantiate a Frame class (lines 5-8), of which the sole member is the constructor. This method's
only purpose in life is to create our widgets. Inside the frame, we have a Panel. Inside the panel we use
a BoxSizer to contain and layout all of our widgets (lines 10, 36), which consist of a Label (lines 12-14),
SpinCtrl (lines 16-20), ComboBox (lines 22-27), and quit Button (lines 29-34).
We have to manually add Labels to the SpinCtrl and ComboBox widgets because they apparently do not
come with them. Once we have them all, we add them to the sizer, set the sizer to our panel, and lay
everything out. On line 10, you will note that the sizer is vertically oriented, meaning that our widgets
will be placed top to bottom.
One weakness of the SpinCtrl widget is that it does not support "step" functionality. With the other
three examples, we are able to click an arrow selector and have it increment or decrement by units of
two, but that is not possible with this widget.
Lines 3951
Our application class instantiates the Frame object we just designed, renders it to the screen, and sets it
as the top-most window of our application. Finally, the setup lines just instantiate our GUI application
and start it running.
19.4.4. GTK+ and PyGTK
Finally, we have the PyGTK version, which is quite similar to the wxPython GUI (See Example 19.10).
The biggest difference is that we use only one class, and it seems more tedious to set the foreground
and background colors of objects, buttons in particular.
Example 19.10. PyGTK GUI Demo (animalGtk.pyw)
Our final example uses PyGTK (and GTK+). Like the wxPython example, this one also uses
a class for our application. It is interesting to note how similar yet different all of our GUI
applications are. This is not surprising and allows programmers to switch between toolkits
with relative ease.
1 #!/usr/bin/env python
2
3 import pygtk
4 pygtk.require('2.0')
5 import gtk
6 import pango
7
8 class GTKapp(object):
9 def __init__(self):
10 top = gtk.Window(gtk.WINDOW_TOPLEVEL)
11 top.connect("delete_event", gtk.main_quit)
12 top.connect("destroy", gtk.main_quit)
13 box = gtk.VBox(False, 0)
14 lb = gtk.Label(