Entry with suggestions

An Entry with an EntryCompletion seems more appropriate than a ComboBoxEntry. As always, the tutorial is a good start.

It's very easy to set up when the predefined URLs list is small and fixed. You just need to populate a ListStore:

# simplified example from the tutorial
import gtk

urls = [
    'http://www.google.com',
    'http://www.google.com/android',
    'http://www.greatstuff.com',
    'http://www.facebook.com',
    ]
liststore = gtk.ListStore(str)
for s in urls:
    liststore.append([s])

completion = gtk.EntryCompletion()
completion.set_model(liststore)
completion.set_text_column(0)

entry = gtk.Entry()
entry.set_completion(completion)

# boilerplate
window = gtk.Window()
window.add(entry)

window.connect('destroy', lambda w: gtk.main_quit())
window.show_all()
gtk.main()

Users are not likely to bother typing "http://" or even "www.", so you probably want to match any part of the URL (e.g. just "og" works!):

def match_anywhere(completion, entrystr, iter, data):
    modelstr = completion.get_model()[iter][0]
    return entrystr in modelstr
completion.set_match_func(match_anywhere, None)

This will test every value in the ListStore for a match, so it's not scalable to huge lists (I mean huge; a 1000 works fine).

Be sure to play with the various options of EntryCompletion, to configure the most pleasant behavior.